No, they don't own the space, but I'd be pretty pissed off if we couldn't park on our street for somebody else's visitor.
It's an every day occurrence where I live. A lot of households have 3 or 4 cars, because their grown-up kids can't afford to leave home, and only space for one on the drive. No-one seems to use their garage for their car (including us, but ours is full of motorbikes). There's room for just one car on the front of most of the houses, unless people block the drive.
If no-one has a visitor, I think everyone just manages to fit on our road, at least at my end of the road. As soon as someone has a visitor or a workman call, we end up with a RL game of Tetris, but with cars.
It's a nightmare atm, as 2 houses in the street are having extensions built and the people across the road are having their back garden landscaped. There's a narrow window around 4.30-5pm, when the builders are drifting off and I can park in my road easily, any later and I have to hope I get home before everyone else does.
My bonkers neighbour has a small car, a drive big enough to take 2 small cars, and a garage. He parks on the bloody street, the idiot. If he can't park outside his house, he parks in the drive, but the minute the space outside his house is free, he goes out and moves the car back out on to the road.
One of these days "his" space will be free and "ours" won't, and we'll have to park our motorhome outside his house.
That will so piss him off.