They could easily factor natural growth and ping you when it feels like bills are getting too close to the cap. Even “bursts” could be allowed x% above the cap

They could easily factor natural growth and ping you when it feels like bills are getting too close to the cap. Even “bursts” could be allowed x% above the cap if you get an email within an hour. The lack of caps is just laziness or a dark pattern by Amazon. There’s no excuse to not implement them, it’s not a hard problem.