It's probably one of those well-publicised "making an example of somebody" cases to make councils and the police look more powerful than they really are, and to get the keyboard warriors frothing on both sides: how dare they prosecute, and how dare anybody use the wrong bins. On the rare occasion that they get a prosecution, they tell the local press, and the council briefly looks big, strong, powerful, and authoritarian. It was like the prosecuting the grannies who hugged their grandchildren when we were not in the same bubble: there were one or two well-publicised prosecutions, to make the authorities look powerful. We didn't hear about the thousands who ignored the nonsense and got away with it.
As we all know, the reality is that the police and courts have been cut to the bone, and barely have time for really serious crimes, never mind things like this. For a "number of times" this has happened, there are tens of thousands of times it hasn't happened, if the amount of fly-tipping is anything to go by. I myself don't need to put household rubbish in public bins, but I wouldn't hesitate to do so if necessary.
Lots of things in the news are not as they seem. If you have to put household rubbish in a public bin, just do it. If you feel conscience about filling them up, look for emptier ones. It's true that bins in high streets often have small apertures to deter this, but there are often other places. Most places with a car park have a bin: motorway services, leisure centres, etc. And for the replies of "just take it to the tip": that very much depends on where you live. I happen to live within a mile of one, in a small town, so not a very busy one. Many of these supposedly ubiquitous "tips" can be nightmarish: needing to book in advance, long queues (even with booking), limited number of visits, etc. And they wonder why there is so much fly-tipping.