It doesn’t suit the French. The French want people in their country spending Euros.
Stamping passports, checking passports, and then there are biometric tests and controls to come, are a pain. Most countries don’t want this nonsense as it is costly and a barrier to trade which is why European countries over the decades worked to abolish internal borders for the movement of people.
But because they did abolish internal borders, they needed to make sure external borders were well protected to assuage peoples fears that ‘anyone could get in’. Well, we are now the ‘anyone’ from an EU perspective, and we, as in the UK, wanted passports stamped and checked. We just didn’t expect the EU to reciprocate. The UK won’t even let school kids in from EU without passports.
We are going to have to invest heavily in the Dover infrastructure, especially when there is biometric testing, otherwise we are vulnerable to long delays every time there is a glitch. We need more buildings, more staff, access roads, the lot. Doing it on the cheap won’t cut it. Brexit is expensive in case you hadn’t noticed. To be fair, the Govt hasn’t either.