Any question answered...

But the point is the inconvenience is recognised and there is some effort made to mimimise it. I feel - rightly or wrongly - that with a bike you should expect to be treated in the same way.

You will be treated the same way if you buy the same insurance products as motorists do, there's a fairly hefty premium on top of basic insurance for getting your own insurer to pay for stuff which they hope to recover later from the third party. If you don't, then civil law applies; the person causing the damage is liable to restore you to the position you would have been in had they not done the thing which caused the damage. You file a claim against them, and ask the courts to rule on the validity of the claim and then support enforcement.