Our children are not water proof. They don't make a sound as they go under, they don't fight, they slide beneath the surface.
As parents, as soon as we know of our little one we spend 40 odd weeks doing the "right" thing to give them the best chance. As they grow we baby proof the house, as they start to walk we are their waiting to catch them, we put training wheels on bikes, we get them driving lessons. All in an attempt to protect them.
In my house it is a non negotiable topic, my children don't have to swim competitively, they don't have to play water polo but they do have to be able to save themselves. Swimming is a life skill, not something we as parents can give up on because we are bored or the lesson conflict with other activities.
Should you have your children in lessons, please stick with it, if you don't please investigate swim schools.