Yes, Texas has a building code. Not sure which but I would guess for plumbing it is the international plumbing code. But Texas may also allow private engineers or architects to perform inspections and submit an affidavit of code compliance. They are thankfully few but there are engineers/architects who turn a blilnd eye to violations as long as the money is green. So the house may not have been inspected. Or the municipality could have hired a blind inspector under compliance with ADA. Who knows these days?
As some one said, everybody has a price and if you find that price, you're in like Flynn.
I've seen a building compliance officer sign off on two chimney throat inspections sight unseen for a jelly donut. True story.
"Hey Carl, there's fresh coffee and Dunkin' over in the office."