In Berlin I remember just two "undercover" guys getting on the subway to check tickets, here in Brussels it's a squad of at least a dozen uniformed goons with multiple attack dogs. These groups are easily spotted and there's social media channels where they leak their locations. Sometimes you'll see an entire bus empty cause someone just announced that there's checks at the next stop. Meanwhile the employees of the company just watch the whole thing laughing.
Nobody can't not afford public transport in EU, it's just that they choose to spend their money on something else and then scream poverty when they get caught.
There are rules, this isn't Vietnam!