Parking on the footway (aka “pavement” in the UK) has become normalized to the extent that many people seem to think it is an entitlement. However, it causes obstructions for people on foot and causes damage to the footways themselves, which are not designed to take the weight of motor vehicles. Even if there is still space for someone in a wheelchair or pushing a double-buggy to squeeze past, it is still an obstruction if two people can’t comfortably walk past side-by-side and is downright dangerous if people have to go into the road to get past. This is also especially an issue for people with sight impairment.
Storage is one of the costs of owning a car; failing to factor that into car ownership is no excuse. If someone has purchased a car without having the space to store it, then the answer is to make some effort to find space, either by buying it or by asking the council whether they can provide it; not just casually to steal the usually small amount of road space that has been set aside for people walking.