I’m not a vet, but help operate a no-kill shelter. We scan cats and dogs of unknown provenance, and occasionally find a chip. We also look for spay-neuter tattoos, which can clue us in to where an animal was fixed, which can lead to the SN vet remembering the animal. Tracking down an owner from chip data is more trouble than you might think. Some companies are defunct. Often the owner data is obsolete.
Often the pets have been passed along to new owners (or variously abandoned, surrendered to shelters, etc.) Every now and then the research, calls, etc. pay off and a bereft owner is reunited with their pet. The process can also drag you into domestic disputes and ethical issues.
The point here is that it often takes more than a quick scan and a phone call. Shelters aren’t legally required to make more than a cursory effort to find owners of strays, but doing this sort of thing is part of our mission.
Vets generally are in the making money business (that’s not a criticism), not the spending time finding owners business. They will perform scans and do searches if a client or shelter asks them to, but I doubt many do this on every animal hoping to find some trouble.
I would think that shelters would be scouring every clue for identity of a possible owner, being in the business of unwanted pets. What you said didn't make any sense.