Unmarked parking - how do you all handle it?

We have an interesting situation in our neighborhood ( townhouses) and generally it hasn't been an issue until this year. Our streets are all county owned, so they can't be lined etc. We have constant issues with people having more cars then they need. ( for example neighbor across the street has 3 cars, and alternates which one he drives every day). This leads to situations where you come home and you have no parking by your house due to guests, neighbors that dgaf etc. Most of us all work together to make sure everyone has places to park, but some neighbors just do not care at all. Any thoughts on how to deal with this? The HOA is pretty useless and just uses the county roads excuse. I wasn't sure if anyone else deals with a similar situation. It's more aggravating then it should be and I'm aware it's sort of ridiculous to get mad over, but it's just one of those little things that really grinds my gears.