Im sure it does happen but without a crystal ball it's hard to ever be certain especially if the references are lying! Lots of people with bio children who blithly talk about "just adopt" would get nowhere near the criteria.
We had to have people that signed off on how we interacted with children, including having to do seperate volunteer work with children (on top of having a child facing job), as well as spending time with family kids
All our finances (hence lottery questions), medical records (including wanting to see if I could get records from a counsellor i saw at university twice)
Loads of references from all sorts of places and people including from the police of a country i spent a gap year in, interviews from our exs (I had to really fight to not have an ex who had a conviction against me not contacted!), family, even our vet 😄
We had endless meetings upon meetings where we were asked about everything from our sex life, all sorts of scenarios to if we would rehome our dog.
Home checks where they opened our cupboards. You can't have done fertility treatments in x amount of time, must have therapy for certain things but not too much that they think you are unstable, have to have strict home set ups, kids be of a certain age etc.
Im not saying that its not for a good reason but it's really hard to see what more they could have added prior (other than the seizing of all electronics)
We also had lots of visits after placement, had to keep a log of every mark etc. This is clearly where there was a big gap in this case
You obviously can blag a certain amount but it's really not as easy as a few lies. It would take months if not years of living a completely different life and answering millions of hypotheticals, references as someone else