Shit happens. Don't use AWS as your only platform, you will get burned sometime. Guaranteed, you will also get burned if you try to host and run your own stuff. How competent you are determines which way you get burned less.
Old story about Chuck Yeager from the 1950's: one time shortly after take-off, Yeager's aircraft suffered an engine failure, and he had to do an emergency semi-crash landing. When he realized that a mechanic had put the wrong type of fuel in the plane, he went looking for the guy. The mechanic profusely apologized, said he would resign and never work in aviation again. Yeager replied something along the lines of "Nonsense. In fact, I need someone to refuel my plane right now, and I want you to be the one to fuel it. That's because of all the guys here, I know you'll be the one guy who'll be sure to do it right."
Probably apocryphal, but the point has merit.
It wouldn't even need to be true seamless failover across AZs right away -- just offering a us-west and us-east Heroku would be enough for me, with shared nothing (maybe billing, or not even that), and then figure out redundancy yourself inside your app. Multiple regions is WAY better than multiple AZs within a region, too -- both for reliability and for locality.
Obviously a real seamless multi AZ/multi region solution would be much more technically impressive, useful to users, and Heroku-like, but they shouldn't let the perfect be the enemy of the good here.
Going multi-AZ, multi-region or multi-cloud will help, each step up that list being significantly more work for increasingly small returns.