From the pictures in the article, it looks like these vigilantes were not cutting the potholes. For keeping it dry you’re at the mercy of the weather. Tamping, let’s generously assume they used a pole tamper, which still does a mediocre job compared to actual machinery. These are public roads where you can’t control who uses them and how, so people will be braking and turning on the repair within a few hours. And again, public roads, these will see hundreds or thousands of uses daily. Given all these conditions, I’ll make an educated guess that the repair will last maybe two months, certainly less than a year. There’s a road near my workplace that two large businesses share, it’s at the bottom of two hills so it gets a lot of water running through, it’s an exit off a ~50mph road so it sees both heavy turning and heavy braking, and it supports approximately 1500 trips per day. Potholes there got really bad, repairs were made with cold mix because the local council was lazy and wanted to shut up complaints. They cut the holes and tamped with a tamping machine (looks like a beefy lawnmower, sounds like a dying motorbike). The repairs lasted less than two weeks.
(Eventually the council relented and did a hot mix repair - essentially cut out and dig up a dozen yard long section of the road and re-lay hot asphalt, as if building a new road - the road was closed for a few days, but that repair is going on a year now and is in better condition than the surrounding road. This repair required a back hoe, an asphalt truck [basically a concrete mixer truck with heating], and a steamroller.)