I'm brazilian and had one of these in my house my entire life. They are not dangerous as it sounds. BUT, gas showers are (please translate to you language):
No. Proper gas powered water heaters have oxygen sensors for quite some time, and ours kick-in before we feel anything about oxygen levels, and it doesn't reset until you get proper amount of fresh air in.
Moreover, newer models are completely sealed, breathing air from outside and directly dumping exhaust outside with a fan, via a coaxial pipe.
I think the point is that while SpaceX had a lot of explosions, they fundamentally approached rocket development very responsibly as regards to human risk. It's not about observation bias.
