From what I have see, I would guess that less than half of websites get Reg Z advertising rules correct.
Sounds about right...and that's a HUGE improvement over the dismal level of compliance years ago.
If the regulators cared about this, they could clean it up in a matter of weeks. If I can search on "rates" + "Member FDIC" and find bank after bank violating the loan (and sometimes deposit) advertising rules, they could too. Print the page, attach it to form letter on agency letterhead, and mail to the bank's CEO. Recheck in one month and tighten the screws on those who haven't improved.