I don't recall ever having actually been asked for transcripts, just for a list of my degrees and the institutions where I earned them. They also asked for writing samples. In my opinion, it's impossible for any company to really evaluate writers until they actually hire them and see the work they produce. A degree is not necessarily proof that someone genuinely earned it and there's no way to be sure that the furnished writing samples were actually written by the applicant.
More importantly, there's not necessarily any correlation between degrees and writing ability, much less writing ability in any specific area. For example, I have formal degrees in Law, Psychology, and History, but there are (admittedly) plenty of topics in Law and History that I don't handle at all. Conversely, there are even more topics in completely different areas (like Business, Communications, Nursing, Philosophy, Political Science, etc) that I handle routinely (and very well) without having any formal degrees in any of those areas.
If I were running an essay company, I'd just want to verify that applicants really have any degrees listed from the schools where they're supposed to have been issued (mainly to to see whether they're being honest with me), and I'd want to review the first few essays to make sure they're up to company standards. In my opinion, it's unrealistic to expect a company to do much more than that. On the other hand, they should be pretty quick to dump any writer whose work turns out not to be good or that generates legitimate customer complaints; and they should have an absolute zero-tolerance policy toward any sort of plagiarism.
Highly-experienced professional writer located in NYC. JD (Law) from NYLS. nycfreelancewriter.homestead.com/services.html