As long as their car park doesn't interfere with your property in any way, or put you at risk, etc., then I don't understand what you're grumping about!
They're in their 80s, so even if they live to be 100+, they haven't got that long left on our planet anyway, and it's their £5,000, not yours.
At their delicate ages, and if they have movement/mobility issues, they probably need their car closer to their house.
Let this glorious old couple live what's left of their lives and keep your nose out!
Working in someone else's home
