1/ As others have already said, these people have no obligation under international law to seek asylum in the first safe country they reach.
2/ As others have already said, most of the people from French speaking parts of Africa tend to stay in France or Germany. Those that you see in and around Calais yes include some of those people but a lot of from Iraq, Afghanistan, Iran etc. A lot will speak English (or some), many have family members in the UK.
3/ The UK isn't seen as a light touch to asylum seekers by most people. Benefits are awful in comparison to many other EU countries, ability to work, learn etc is very limited and something that takes a long time.
4/ UK is still seen (amazingly, somehow) as somewhere safe, law and order and a good society. You can thank decades of UK TV, Musicians, historians, books etc for that. If you travel more around the world you'll notice just how much UK (and of course US) culture has permeated through.
5/ UK has taken nothing like the number of asylum seeks that France and Germany has.
The simple answer to all of this has already been said. Set up a processing facility in France and people claim asylum there. But oh no we can't do that, because a) the government can't even provide enough customs officers for Ferries, Eurotunnel or half the airports in the UK as it is, b) would mean providing an actual solution so no longer can the government blame the migrants for all the wrongdoings in the country and c) removes Priti Patel's reason for being in government.
This is why France does what they can, but not everything they can. Because there is a solution but the UK refuses to do it.
