Not to be obtuse, but some would say you're reversing cause and effect -- that the $10k and exhaustive background checks are the reasons that adoption has better success rates. I couldn't be less of an expert, but it's hard for me to imagine that the solution is as simple as "adoption is always better."
It does absolutely seem like there are many wonderful homes out there who aren't able to adopt because they aren't quite well-off enough, or the couple is gay, or some other factor that a reasonable person could look at and say "this shouldn't disqualify you from adopting."
Agreed that success rates are irrelevant to this conversation and it's certainly not true that adoption is always better. I think that most people would agree that the relative stability of having permanent parents would be, on average, better than being in the awkward foster system for ages. The foster system is meant to be temporary until a child can be placed in a permanent home [1] but 29% of children placed in the foster care system are stuck for at least 3 years [2].
It does absolutely seem like there are many wonderful homes out there who aren't able to adopt because they aren't quite well-off enough, or the couple is gay, or some other factor that a reasonable person could look at and say "this shouldn't disqualify you from adopting."