It's always been the same. Plenty of people that go fishing don't know or care what the law is. Most of the general public and the police don't know that there's a closed season. The number of EA bailiffs is pitifully small. They have to target venues where they can check the greatest number of anglers in the shortest time possible. Patrolling miles of river to check/catch a small number of people isn't the most cost effective plan. On a bank holiday weekend, from Easter onwards, it makes a lot of sense for them to trawl the big commercials. They get to check hundreds of anglers and catch more illegal/unlicensed anglers that they would trying to cover miles and miles of river.
All this comes before you consider odd little local bye laws. I've limited knowledge of those outside my area, but I can quite legally fish my local rivers for trout with worms. Many controlling bodies don't allow it, but many do. You can't look at someone trotting or legering on our local rivers in April/May and know that they are breaking the law. I understand that similar bye-laws exist in other parts of the country (South West and North West?).
If there's any chance of out of season anglers being caught, the people observing them will have to report them to the EA/police. There's little danger of routine patrolling picking them up.