One thing I don't like about default ServeMux is that addresses are prefixes. So `mux.HandleFunc("/"...)` always handles _everything_. And there is no easy way to say "no, just handle exact matches, plus maybe ? queries". As gorilla/mux does. I don't think that is changed in the new go?
From the proposal: "There is one last, special wildcard: {$} matches only the end of the URL, allowing writing a pattern that ends in slash but does not match all extensions of that path. For example, the pattern /{$} matches the root page / but (unlike the pattern / today) does not match a request for /anythingelse."
But that’s not backwards-compatible, sadly, so this is going to remain a historical wart.