I could have made the same mistake. Their customers are highly technical engineers applying to FAANGs and other top companies, I'd personally expect a greater understanding of terms and payment details from that cohort.
They don't, as far as I can tell, vet their customers. They deliberately cast as wide a net as possible, so it was entirely foreseeable they were going to hook some less sophisticated users.
This is a lower scale and lower cost version of the for profit bootcamps and IT schools. Yes, if you go in with the tools you need to succeed, you will probably gain something and get a good start at a FAANG or similar. The programs cannot work miracles and have a vested interest in casting as wide a net as possible even though that's a disservice to their customers. This service figured out they need to reign in that net to confirm people can actually pay their cost.
The vast majority of the people signing up are going to be wannabe engineers - what percentage are actually highly technical needs to be determined.
Tech has become popular because of the salaries, the amount of people interviewing has heavily increased, but the talent levels are quite diluted. Especially because any engineer worth their salt is off the market in under a month right now, if not shorter.