Can I be frank please without being unkind @Shewhomustgowithoutname
I think you are being unreasonable because you are "predicting" people's future behaviour and using this as a reason not to pay £3,000 to drop your kerb.
And your "prediction" is based on their perfectly legal behaviour at the moment.
It doesn't matter if someone came out once and sprayed a few white markings. Until a sign goes up saying "Works taking place on XX.YY.2019", then people are legally entitled to park.
People don't tend to look at an empty patch of land outside someone's house and say "they could potentially park there so I'll avoid".
They look at the legal markings on the kerb. Is the kerb unbroken with no lines or restrictions? Great - I can legally park.
So you're dithering on dropping the kerb, based solely on the fact that people have legally parked outside your house and "ignored" the fact you might have a patch or two of land where you could "potentially " park...
Do you see what I mean about how silly it sounds?
The lines on the road/dropped kerbs are the only way we can communicate our legal intentions. I can't go door knocking every time I see a patch outside someone's house that might look like a parking space.
YABVU and please don't keep ascribing it to being a single mother etc.
Your neighbours don't need to be kind to you and allow you to have off street parking when you haven't paid for it by normal means of contacting the council and making it legal and enforceable.