[IAmEveryone]

It's simply "you touch it, you (might) own it". The same principle applies, for example, to first aid, which is why "Good Samaritan" laws exist shielding you from liability. I generally sympathise with your point of view, because I really don't know how you can actually make a pothole worse by attempting to fix it. But if someone can make such a case ("they fixed it with road-coloured cardboard paper and I didn't see the hole below"), then yeah, they are liable.

The city is just giving advice in this case. If someone where to harmed by one of these fixed potholes, the lawsuit would be between that person and these "pothole vigilantes".

[hermitdev]

> I really don't know how you can actually make a pothole worse by attempting to fix it.

My first thought would be using substandard or incorrect materials. Say, using concrete in an asphalt surface. You quasi cover this with your cardboard part of the comment. Perhaps an incorrect mix of aggregate to asphalt might have different thermal properties. If the pothole expanded more/faster than the surrounding material, it might make it a lot worse. Also, if your materials are not safe to drive on while setting (like my example, filling a hole with concrete). You'd also be endangering yourself and others while attempting such work as you'll be unsuitably marked and lanes won't be properly barricaded for your work.

[ensignavenger]

"I really don't know how you can actually make a pothole worse by attempting to fix it"

You have clearly never lived in the town where I grew up :)

[schoen]

> "you touch it, you (might) own it"

Perhaps compare https://news.ycombinator.com/item?id=10367855.