We have three cars and three off road parking spaces but they are single file. If I need/want the front car out I have to shuffle all three. Yes its a PITA but the alternative is to park outside our front garden which is directly opposite two drives. They
could still get on and off their drive with one of our cars there but it would make their life more difficult, which I'm not prepared to do. On the odd occasion I did park out there for an hour or so I'd have the car half up on the grass.
This was the situation for 8 years then Covid hit and my neighbour brought home a mini bus daily and parked it outside our house. Nothing stopping him doing that but I found it quite ironic that he gave zero thought to those two drives he'd near enough blocked. He does have a drive but doesn't use it as the layout is pretty terrible plus another neighbour has an arrangement with the person on the other side of him that he can park his van outside his garage... as long as he leaves enough room to get the door open, which leaves next door with a tricky parallel parking move to do every time they get home or want to go out.
Words were said (not by us) so the mini bus then moved outside his place and their car went to the hammer head at the end of the close. Several months of cat an mouse then went by where the person who's house was in front of said hammer head would claim the space and as soon as they went out the other neighbour would claim it back. Hammer head person has off road parking for 3 cars, 4 at a push. They have 2... That ended up in words being said with both feeling the other was unreasonable.
So... we now have a fantastically complex situation where 5 houses are annoyed with at least one other household... all over parking. Thankfully the mini bus is gone and its no longer an issue and everything is back to normal but it just shows how one extra vehicle can cause no end of issues. Also how a "I can legally park there and it makes my life easier so deal with it" attitude would have made this situation permanent if I decided to make everyone else suffer because I choose to have a toy car.
OP - a garden is a garden, not an unconverted drive way so get that thought out of your head for a start. Also you say they don't have drives but also that they park zero cars on their drive so which is it? If you mean they don't park on their garden then... well... that's not what they are for