If you have to be a domain expert to configure it correctly, as is clearly the case with AWS since configuring it is a whole separate industry, then for all intents and purposes it is not there as far as a regular user is concerned. If it helps, imagine a Cessna pilot who's suddenly asked to fly a big intercontinental aircraft without any of the assistance features turned on. All the controls are there, but as far as the Cessna pilot is concerned, they can't fly it.
Billing limits, as in, a hard limit over which resources will shut down and I can be sure I won't be charged over that limit? I'm pretty sure that doesn't exist.
You have to configure (correctly) an AWS IAM account with permissions to run actions you have to specify when budget amounts are hit. There's no simple 'Do not spend more than $X per month' setting. You have to understand AWS's auth and roles to set a limit using an action.
Monitoring, alerts etc are not the same thing as being able to put a cap on the amount of money Amazon can charge your account for services per billing period.