This. ^ I can't get my head round it. Posters saying their kids took many years to learn to swim, others saying they're 3 years in and at stage 5, people talking about 50 lessons a year and what it's costing them, and it's been thousands of pounds so far. I am baffled. It's longer than a University Degree. Even learning to drive takes much less money and time and lessons than some peoples children are taking for their swimming. One poster said that her DC struggles to pick things up, and took 14 years to learn to swim. And one poster said theirs took 20 years! I am baffled. 
Like you @Jujujudo - pre the year 2000 - everyone I know, family, friends, old schoolmates, my DC, (now in their late 20s,) their friends etc etc, all learned within several months. As I said, it's swimming, not brain surgery. Even children who weren't so academic and struggled picking some things up, managed to learn to swim within a few months. Taking multiple years, and 100s of lessons costing 1000s of pounds, is just like a parallel universe to me. Obviously happens as I'm sure people aren't making it up, but surely there has to be a point where you say 'enough is enough. I am clearly being ripped off here!'
And what is this stage 5, stage 6 stuff... Once they can swim a length, unaided, they can swim. After that, the parents can take them swimming 2-4 times a month, and they can develop the skill, and get some strength in their swimming. As a poster said, they don't need to learn butterfly and backstroke and fancy synchronised swimming. They just need to be able to swim. As I said, once they get the basics, anything else can come later when they go swimming with family.
Going to swimming lessons that are costing 1000s of pounds and lasting several years, or even longer, like 10 to 20 years, and going through stage after stage after stage is utterly bonkers. Parents are legitimately being ripped off, and someone needs to put a stop to it. Fact is, swimming needs to be in the school curriculum. It should be free, it should be for every child.