...are elderly people on holiday expected to just get smacked in the face with a ball, or leapt on by kids, if they dare to venture into the pool past 6am
Weirdly, elderly people and 'boisterous' children co-exist happily in my local pool during public and family swim times. This is because they are all recreational users of the pool and it is easier to steer clear of a family playing ball or kids doing cannonballs than it is to keep on looking behind you to see if there is a swimmer plying a straight line from one end to the other.
In my local pool, in the main pool, there is even a chair lift device for people who are normally wheelchair users, who can thus use the pool during all opening hours. They are assisted out of their wheelchairs and into the chair lift device, then lowered into the water. When they want to get out they return to the chair lift and whistle up a lifeguard.
There are also several pool wheelchairs that can be wheeled into the thigh depth area and locked in place so that people in them can spend some enjoyable time in the water while children run all around and the fountains play. (They are chairs designed for pool use, not dry land chairs.)
Children jumping in tend not to leap straight onto others. Even if their parents have not warned them not to do this, they themselves will learn the hard way that this hurts. By the same token, elderly people can also usually see well enough to keep clear of children who are jumping in. Maybe they avoid a certain spot where children are gathered to jump in and climb out repeatedly, or maybe they stay a little out in the water in case of random jumpers. Lap swimmers otoh, depending on the stroke, might have a hard time seeing what or who is in front of them, and in the case of the backstroke and crawl (depending on your form) you can forget about seeing others altogether.
I shudder to think what might happen if some dick decided to do lap swims while someone not enjoying full mobility was floating on their back, playing ball with grandchildren, or catching small children jumping in.
Do you swim much? Your objections to common sense observations seem to indicate that you are not altogether familiar with how pools work, or safety concerns.