No sensible industry throws away market share. There's no reason why only effective EU membership (which must be a non-starter as nothing really changes) or an existing inadequate practice, has to be the only options. That's what negotiations are supposed to be about, to create bespoke agreements to maximise benefit. EU industry simply seems cowed at present, but who knows what's going on behind the scenes.
It'd be foolish to assume that insisting on cutting off one's nose to spite one's face would result in the best outcome. EU industry doesn't stand to gain the freedom goal a leaving nation achieves, and which makes minor temporary economic disruption worthwhile. It only has potential loss by continuing to act the intransigent player in negotiations. But if by inactivity they allow issues for themselves, that's their own fault.
The UK government need not be more clear. Obviously they'd want a true trading block agreement which has low tariffs and no obligations to give control over unrelated national matters to outside power groups. It's about trade not diminishing one's nation to be a subset of a large block controlled by outsiders, and not even able to have full secure control of it's own borders. If the EU dropped the, "We're in control, you'll do as you're told", attitude then that'd be a good start.