Why are so many kids still unvaccinated?

I'm at a loss to explain the poor uptake of COVID vaccine among young children.

When vaccines first became available, in what now feels like another life, Canada was slow to start due to supply problems. But it very quickly made up for lost time and soon became one of the most highly-vaccinated populations in the world. At least its adult population.

When vaccinations became available for younger people under the age of 18, the take-up was much lower and slower, and vaccinations among under-5s were even fewer when a vaccine became available for them. Vaccinations for under-5-year olds is currently languishing at around 6%, even fewer have second doses and boosters. Among those under 2-years old, the rate is even lower, as low as just 1%.

Now, obviously, it's not the kids who are making the decision not be vaccinated. It is the parents of those kids, the same adults who chose to get the vaccine for themselves. So, what is the logic? Why would they get the vaccine for themselves but deny it to their kids, the same kids who are mingling unprotected at schools and kindergartens and preschools with other unvaccinated kids (and contracting COVID in droves in the process, from anecdotal accounts, although testing is almost non-existent now and there are few to no reliable statistics any more)? 

The vaccines are proven efficacious for kids, and have little to no side-effects. Those same kids have many other vaccines (and indeed are required to in order to attend school). So, what's the deal?