Based on my experience with drunks around roads, the cars generally aren’t at fault. People do real stupid shit when they’re drunk, like taking a highway tunnel instead of walking the extra 500m for the pedestrian tunnel. You can have all the protection you want, but if you’re to drunk to walk straight and end up in traffic there’s nothing to protect you. Same shit also happens with train tracks every now and then. Hell, I’ve even read stories about traffic deaths when drunk people and bikes collided (especially if the person on the bike was elderly).
If you’re drunk enough that you can’t navigate the streets about as well as when you’re sober, take a cab or the bus or have someone pick you up. That’ll also help in case you run into health issues because of excessive alcohol intake.
As a bonus for drunk accidents: because of the delayed response you may walk away from certain crashes with fewer injuries because your body doesn’t tense up to attempt to distribute the impact. On the other hand, you’re much worse off with other accidents.
The possibilities are limited and the legal responsibilities untenable. It’s a fun idea, though! Technically there’s nothing preventing you from distributing WiFi access points in your neighbourhoods and having everyone hook up their home network into a local, shared mesh for instance.
With a private IP address range (probably best to use IPv6 to prevent conflicts there, but you can try to allocate private IPv4 addresses if you like a challenge) you can even have your own internet next to the normal internet and use both.