It’s total safety that’s important not individual aspects of safety. Clearly there are many disadvantages, but when comparing it to 15 hour flights there are several advantages.
For example shorter flight times mean fewer chances for in flight human errors. Another is in flight medical emergencies can be more quickly reach a hospital. A few aircraft have been shot down which is again much less likely, etc etc.
Initially it’s going to be risky, but give it say 50 years and it might actually end up being the safest option for ultra long distance travel.
One aspect can ruin the total safety. It can't be more safe than the least safe part of the trip. Sure, maybe in 50 years we'll figure out something better. But SpaceX is talking about flying long haul Earth to Earth routes with Starship, not a hypothetical future craft.
A 747 built 1970 is very different than a 747 built in 2020. Barring PR issues etc, SpaceX could be using an ever improving version of Starship for a very long time.
For example shorter flight times mean fewer chances for in flight human errors. Another is in flight medical emergencies can be more quickly reach a hospital. A few aircraft have been shot down which is again much less likely, etc etc.
Initially it’s going to be risky, but give it say 50 years and it might actually end up being the safest option for ultra long distance travel.