They're just concern trolling for imaginary ambulances that might need to make their way through again. I remember seeing a Hong Kong color revolution video back when leddit was fawning over them and they blocked highways then. An ambulance drove by and stopped, and the color revolution agents simply scooted over to let it through.
The only reasons this doesn't happen in the US are because nobody can afford an ambulance and because someone always tries to Truck the protesters to death within minutes anyway.
well that and if you've ever been on an SF Bay bridge you'd know a single car stalled could snarl traffic up across the whole goddamned bay area for hours and no one is going fucking anywhere