Around here, nearly all home inspectors do not offer mold testing. Guessing that is pretty standard throughout the US. Its manipulating numbers to make a sale.
It’s the logic as saying nearly all injuries from car accidents are from people riding in cars.
I don’t have anything to sell. In Florida where mold inspections are common with home inspections, nearly all mold suits are filed against home inspectors who didn’t offer mold testing. If you test for mold, and you don’t find it, your client can’t sue you for not looking for it - you more than just looked for it, you tested for it. And if you do find it, your client can’t sue you for not finding it.