...which have been vaccinated by now (unless they are young), so why penalise kids for a risk assessment which doesn't exist anymore?

You know most parents with "kids" are under 50, right? OP is complaining that the vaccination rate <50 is too low.

What's your solution to kids that have young parents? Every child of people 50+ years old go back to school, and the others stay behind?

Young parents are also much less likely to get severely ill than older parents.

So the ones that do get infected and die are just part of the sacrifice?

People die of the seasonal flu all the time too. We don't shut life down over it. Covid is much much worse than the seasonal flu for many people. For others, it's less dangerous. That said, people still get hit with it.

You can't get to 0

I don't understand the point of your comment if you admit that Covid is much worse than the seasonal flu. We don't shut life down over the season flu, but we might for a much more dangerous disease. That's the whole point.

That statement is demonstrably false. UK is only at 8% vaccination rate overall. 60% of eligible adults have had a single dose, but that 60% is heavily biased to the elderly and those with pre-existing conditions.

The single dose has been shown to provide good protection in the short term, so the 60% number is more relevant than the 8% one. Although percentage of total population rather than adult population would probably be a more accurate representation.

Because vaccines are never 100% effective, and there are plenty of people who legitly can't receive one due to other medical conditions.

An honest question: At what point should we stop trading the healthy development of children for a reduction of risk for certain vulnerable parts of the population?

When everyone that wants a vaccine gets one (well, two).

And I mean everyone in the world unless we a) close the borders completely for absolutely everything, or b) implement covid passports.

The general decision seems to be at the point when vaccines are widely available.

Which is in just a few months.

In some countries at any rate.