What evidence do you have that the labor laws are a response to polish domination of freight, or that those laws would would somehow only cause polish carriers to become unprofitable?
Basically the law change is this:
Now, if you are Polish truck driver employed in Poland, you are subject to Polish tax and labor codes, including things like tax rate, minimum wage, etc. What France wants (and what was passed, but is not in effect yet) is that if said truck driver crosses the border of another country (say, France) he should be subject to that country tax and labor code. Which is riddiculous, because the driver does not change his tax residence, he just enters France for a few days it takes to make a delivery, and then comes back to Poland.
It would be ridiculous, because the factory worker would be working at a company domiciled in the other country. That is because, a company in one country can not just open a factory in another country without having an entity in the latter country.
Consider an alternative situation: Franz is employed in Hungary as a writer of fiction, but crosses into Austria many days and uses wifi to work there. Should Franz be paid Austrian minimum wage?
All kinds of other local laws apply just by entering a country.
Local laws do apply, but generally one can not just enter another country and work there. Very often one is specifically prohibited from working in another country without a visa.
But that's not really the situation here: it's a business providing services for customers in another country. You send a driver abroad for a few days, that should not make him subject for local tax and labor laws. If you can prove that said worker spent significant period of time there (most tax treaties use 183 days as a rule of thumb) then that's a different matter.