Not dying from Covid does not imply not being susceptible to the disease - it has a sufficiently large proportion of bad long term effects so that we would want to prevent everyone, including children, from getting sick with Covid even they aren't likely to die from it.
Death rate is not the only measure, and it's not the proper measure in this case.
E.g. a recent Norwegian study (https://www.nature.com/articles/s41591-021-01433-3) had roughly half of young (16-30) people with mild covid (non-hospitalized) still showing harmful effects six months afterwards; so the covid risks/consequences are much worse than any currently known vaccine side-effects even for mild covid in young people. Heck, we're even seeing long-term problems for some people for whom the initial infection was asymptomatic - this is a nasty, risky disease to get, not comparable to diseases that just put you out of work for some time and you're fine if it doesn't kill you.
Death rate is not the only measure, and it's not the proper measure in this case.
E.g. a recent Norwegian study (https://www.nature.com/articles/s41591-021-01433-3) had roughly half of young (16-30) people with mild covid (non-hospitalized) still showing harmful effects six months afterwards; so the covid risks/consequences are much worse than any currently known vaccine side-effects even for mild covid in young people. Heck, we're even seeing long-term problems for some people for whom the initial infection was asymptomatic - this is a nasty, risky disease to get, not comparable to diseases that just put you out of work for some time and you're fine if it doesn't kill you.