The home assessor isn't just assessing your circumstances. They are also assessing you, and whether you know what you're in for.
The biggest thing the rescues want to avoid is bounce-back.
Getting a rescue isn't the same as getting a puppy. Rescue dogs come with baggage, and bounce-back can be the difference between a successful integration into a family, and a fearful and shut down dog.
People who have never owned a dog or haven't really been responsible for one quite often have very unrealistic ideas about how much work it can take to rehabilitate a rescue - mostly it's love, reassurance and patience, but those things are usually required in vast quantities. If the rescue centre gets it wrong it can ruin the dog, so there is a huge amount of pressure to match successfully.
I got my big boy from Spain when he was only 16 weeks, but he was bewildered, and terrified and it took months and months before he trusted me. Once, my husband shouted upstairs to one of our sons about something and my poor dog dropped to the ground and wet himself in terror.
You have to unpick their past because you never fully know the back story.
The dog will settle if managed properly and soon enough you would have no idea it had ever had an issue, but if you aren't there for that time to put the work in, it won't happen.
So the rescues are strict for a reason, and people who are planning to change their situation if they need to, have a young child who has young friends and may spook the dog, and work full time leaving the dog unsure and afraid for hours, have an awful lot of red flags.