Just heard the other day from AOC that the new COVID relief bill had such a ridiculous clause that no one even stepped up to claim they put it in, so they just removed it without any resistance. The whole bill authoring model is currently broken, representatives receive ridiculously little time to review what to vote for and massive bills are basically take it or leave it.

For the specific tax law that taxpayers have leveraged that the IRS now doesn't like, I'm pretty sure it came from an IRS nerd. The Residual Profit Split Method. That one could only have come from a new grad.

Individual members may not, but they probably have legislative staffers that do, and the staff (majority and minority) of the tax committees, who prepare and distribute analyses of all tax bills, definitely have the skills to read, understand, and explain the implications of tax bills.

Members of Congress may not care, but they definitely have access to a competent understanding of proposed tax laws.