By your logic should we allow kids to buy alcohol, cigarettes, and drugs because it inconveniences adults too much? These are tired arguments from adults who are terrified that it might take 30 more seconds to access their hardcore porn.
By your logic, we should allow the government to search our phones, computers, cars, emails, etc before buying alcohol, cigarettes, and drugs because "it might save just one child!".
Don't pretend the left wing is any better about this particular issue, though. It's the libertarian checks-and-balances constructs built into our form of our government that's resisted this sort of totalitarianism, not the principles of mercurial politicians.