In Brazil it`s a federal law that does not allow foreigns pilots to fly commercially, in Europe it`s the decision of the airlines.
A private airline can do what they want, but if a govt does it, especially in a country where many of their citizens work all over the world, where do you think the many former Varig pilot are flying this days? I call that discrimination.
It`s a fact in Brazil a legal resident does not have the same rights as a Brazilian, I`m not talking about the right to vote but many things that a foreign can`t do, some which are a true shame, like having a simple bank account on a Visa.
I have/had 4 different pilot licenses from various countries, ANAC is a huge mess, one of my licenses comes from a far less developed third world country, got my licenses converted in just over a week, and there was never any questioning about my papers. Yes ANAC is getting better that is true.
In Brazil you can easy rent an airplane as long as you get checked out, I have soloed cessnas from a flight school in Rio. If you network a bit there are many private owners that have planes sitting around that will let you fly it, maybe not solo right away...I can point you out some peoples in Rio.