The point poorly expressed is that public markets transactions are highly scrutinised, and it is easy for shareholders to be highly litigious toward the directors.

The directors therefore have a strong incentive to only accept offers at a normal premium to current price, which seems to be about 30% by back of the cigarette packet maths.

Bidders therefore have an incentive to bid around 30% so their bids are more likely to be accepted.

The key thing is an incentive to avoid liability and get deals done. If the equilibrium was 80% then bids would be all at 80% and there would be less of them.