What could be the problem with allowing people to choose whether or not to get vaccinated? Including children (who, depending on their age, may not have a clear understanding of what the best choice is).

In fact, if—for whatever reason—you decide one way or the other, in any case, this does not create problems for yourself or others, since the decision was made consciously (including the possible consequences).

From another perspective, making it mandatory and imposing a certain protocol does not make life better for anyone, since there is no real benefit.

This is not a matter of security checks, which prevent potential criminals from causing harm (both to themselves and to others).