Sorry I disgree with most of your points, especially the comment that "the majority of trees on Ancestry are completed by people simply collecting names". As with ALL data, the onus of checking that the data is correct lies with the person receiving the information, not the one giving it. Yes, a lot of information posted on Ancestry is wrong, but it is the odd snippet which is correct, that can find a way through a brick wall that makes it all worthwhile.
With regard to people in the US putting in American counties instead of English ones, that is partly the fault of Ancestry themselves, because on the US website there used to be a drop-down box to enter counties, instead of text entry, and it was all too easy for people to select the wrong one.
And lastly.... everyone makes mistakes, including the people who filled in the census forms, and the enumerators who transcribed them.
P.S. If you don't want Ancestry hints, you can exclude a tree in database searches in the preferences section for that tree.