AWS may charge more for egress, but that’s not high enough for it to be a concern for most clients.
A bigger, independent concern is probably that there should be sufficient redundancy, backups and such that allows for business continuity. (Note again that I’m not saying that all companies make full use of these features, but those that care for such things do. Additionally, I’ve honestly never heard of an AWS DC burning down. Either it doesn’t happen frequently or it doesn’t have enough of an effect on regular customers, both of situations are equivalent for my case).
Most businesses choose to prioritize the second aspect. Even if they have to pay extra for egress sometimes, it’s just not big enough of a concern as compared to businesses continuity.