As indeed was I. That would have been a threshold ‘fixed…in advance’.
Which indeed it does and which are indeed a feature of some systems using the D’Hondt method. But not the UK Euro elections.
Which is irrelevant, as the elections for the Scottish Parliament use a completely different system (albeit another form of PR).
But the thing is that there is no need at all for any of the voters to understand how the seats are actually distributed. All they need to grasp is that the seats are allocated roughly according to how many votes are cast for each party. (‘Roughly’ here actually meaning by a complicated mathematical formula.) Trying to vote against any particular party is largely pointless; the sensible thing is to vote for the party that you think best represents your views, which is what most people do anyway.
The real problem, which is one only likely to increase, is that using different PR systems for different types of elections only confuses people.