A few more …
Ditto Diana
I agree with Ray, I wouldn’t loose any sleep over them. Could of been less than desirable compaction of the soil in these areas, possibly poor concrete mixture, or both.
Try some of this to fill the cracks, works good and it’s paintable.
http://www.azpartsmaster.com/shopazp/Caulk+%2D+Dap+Concrete+Sealant+%28DAP18021%29%2Eht ml
The garage floor is typical of shrinkage cracks.