We have similar issues here too. I live in a lovely seaside town with lots of locally owned shops, that I'd love to support, but their opening times are just so awkward, and downright random, that I just can't get to them.
I've tried to go to our little hardware shop about 3 times lately, but ended up ordering it online as it was shut every time I made it into town.
There's always lots of moaning about how bad business is, or the council are killing off tourism, car parking charges are to blame, etc, etc, etc, and I agree, these are issues, but also, if a shop is never open in the first place or has really awkward opening hours then all the free car parking in the world isn't going to help.
I took my children for a wander into town after dinner for an ice cream a couple of weeks ago. It was the Easter holidays, gorgeous evening so loads of people having a mooch in town, but everywhere was shut (the ice cream shop's opening hours are 10am - 4pm). All the little knickknack shops and gallery type places which are very seasonal/tourist dependant were shut. They could have made a killing. We ended up Sainsbury's and bought a multi pack of Magnums, I'd have much rather bought the lovely locally made ice cream that the shop sells, but if they're not open, I have to take my money elsewhere
I totally understand that the owners want to be off enjoying the gorgeous weather and the school holidays too, but when you're running businesses like these, you have to make hay while the sun shines