Perhaps the constant demonizing of public services by private interests, (who btw often rely on government contracts to function), and certain politicians bought by these interests could be a contributing factor in why not?
But let me hear about how private healthcare and broadband is killing it please.
(I have Comcast, so it's not like I've even got the "best", but I'd way rather deal with Comcast or Blue Cross than any government agency...)
Let me put it this way: Comcast is the only reason why a lot of the US doesn't have gigabit internet at cheap prices.
It's a vicious circle, but not an inevitable one. There are plenty of examples of well-functioning government departments, and in some countries there is no significant difference between the performance of publicly run institutions and their private counterparts (although there is of course plenty of variance within both of those groups).
Of course it has: pissed-off voters. Mismanaged government-funded institutions such as DMVs or social security systems are a regular troublemaker for politicians.