The IRS getting okay work out of a contractor is not the same as a random food manufacturing or trucking company trying to contract work out.

Consulting companies, especially the largest ones, are known to employ more hacks than competent folks - because they can. (This is the “lowest cost” you mentioned.)

Just read the stories here about the big names.

Succeeding in not being sued - most of the time - doesn’t mean you’re doing good work or good business.