I have to admit. I feel better now.
If so many of my esteemed colleagues, 
, are arguing over this, I don’t feel like a moron for not knowing it when I looked at it.
For the “legal” requirement, absolutely. The old joke … “the code is not whats written in the book … the code is what the building official says is written in the book” … actually has some truth to it.
For a Home Inspector a lack of blocking at joist laps over beams and walls is a “defect” (Reference Pg. 129 of “The Complete Book of Home Inspection” by Becker, Principles of Home Inspection" by C.D., et al).
If an AHJ later comes along and interprets that blocking is not a “legal” requirement for certian situations … who cares. HI’s do not enforce or interpret codes.
And an HI is not just looking for joist lap blocking over beams/walls. It is also considered good practice to have bridging (joist blocking or cross bracing) about every 8 feet max. The intermediate bridging/blocking is usually the sticky one for HI’s (helpful to stiffen up floors, but controversial on if that should be flagged for 2x12 and smaller joists as it’s not required by model codes) … with blocking at joist laps the no brainier to look for doing a home inspection.
JMO & 2-nickels … 
I do not quote code, but in my locale, admittedly in a seismic zone, the local authority requires solid blocking at all bearing points. In my personal opinion, I would call the lack of blocking a defect (and have many times). Incidently, there is a recycled timber company not far from here. I recently saw, at their yard, 36’ long 2X14’s being loaded onto a truck for delivery.
Unfortunately, trying to retrofit ‘codes’ by home inspectors after-the-fact is really the heart of the problem here…
If an existing structure one is inspecting has been built to Code standards that do not require blocking between joists where they overlap a girder, then the installation is a legal installation and requires no correction…no ‘calling out’. Period. The installation has been done correctly. Period.
The only time a home inspector may have some grounds by which to cite a suspected ‘problem’ such as the one we are discussing, is if he is inspecting a new building that is currently being constructed.
It is not uncommon for code inspectors to sometimes ‘miss’ standard inspection items and the home inspector has a better case of pointing out what he suspects is a ‘defect’ because the process is ongoing and the Code under which the structure is being built known.
Even then, however, it is ultimately the authority having jurisdiction, the code official, who gets to make the final call…and the Code Official has the authority to waive strict Code requirements when he deems fit.
Trying to point out supposed code ‘defects’ by home inspectors becomes a very slippery and extremely grey process in most instances, and a far less sound practice than that performed by Code Inspectors at the time of their inspection.
Appealing to ‘Codes’, then, becomes very difficult for home inspectors no matter what type of structure is being inspected, and without knowing the code in effect at time of construction or extenuating circumstances noted by the Code Official at the time, or even what portions of the Code that may have been stricken or amended for local adoption, quite impossible.
In my jurisdiction, if a home inspector tried to point out the non-blocked joists over a girder in the above photos, I would tell him he was wrong. I would testify to the same if ask for my opinion as a professional witness.
Blocking between joists a good practice where they terminate over a girder in a non seismic zone? YES
A requirement under Code? Absolutely not.
Homebuild … you have to understand that Home Inspectors are not doing a code compliance or code based inspection. It is an installation and performance based inspection, that really isn’t about the legal construction requirements. Many HI’s do use current model model codes like the IRC as a guide for installation related issues, and possibly certain local restrictions if they are aware of that. But apparent “defects” should NOT be flagged as a “violation”. Only the local AHJ can make that determination.
One example is an older home with 2-wire circuits and all 2-prong non-GFCI receptacles. It may have met the local codes in effect at the time time of construction, and be completely legal (not known). That is for others to decide. But the receptacles should get flagged as a defect with a recommendation to upgrade the devices without a doubt.
Then take the example here of no joist lap blocking on say a home under construction where an HI is doing phased inspections. It is beyond a home inspection to know exactly what the local codes are, and sometimes more importantly how the local AHJ interprets those requirements. But the lack of blocking should get flagged, and let others make the call if thats not a legal requirement.
I have even recommended things on new construction that I knew were not a legal requirement of the local building codes. Locally it is considered good practice to add bridging in the middle for larger floor joists like 2x10’s or 2x12’s that are at the upper span limits (in addition to the rim joist attachment and lap blocking, locally interpreted as being required by code). So a lack of that bridging may get flagged, and it is then up to the client to decide if he wants to pay the framer to add the mid-span bridging that the AHJ doesn’t require (as it’s not an IRC provision or usually a “legal” local code requirement).
JMO & 2-nickels … 
See Below:
Why would a good contractor want to ‘just get by’, just do the bear minimum required by local law? Why not do the best practice?
Money!!!
Nice Will.
Marcel