Maintainers often pick permissive licenses specifically because they want companies to use the code. They want their project to grow and be adopted, and they reason that GPL would stifle adoption.

I don't really like the tactic of making your code as convenient as possible for anyone to grab off the shelf when they want to use it, and then later turning around and saying they should pay you. Why not do the payment part up front (by GPL-licensing the code and then selling dual licenses to interested companies)? Because then you wouldn't have any takers. Better to wait until people have integrated it into their systems before informing them that they ought to pay you.