A Politico article on the events in Northern Ireland this year mentions that bus hijacking and burning had a bit of a history/"tradition" during the Troubles.
Police said two masked and armed men stopped the bus and ordered the driver off, before dousing the inside of the otherwise unoccupied vehicle with fuel and setting it on fire. Such roadside hijackings, particularly of buses, were common during the three decades of conflict over Northern Ireland known as the Troubles, but are a rarity today.
I can't seem find much about the older history of these bus events, unlike say for bonfires.
So, how did bus hijacking/burning start during the Troubles and what was the extent? And how e.g. were targets chosen? Did people burn down busses that (mostly) served the "opposite" community or their own, back then?