Earlier quoted context omitted.
I agree. Why is this an hourly charge? Same for endpoints in a private subnet. Are there actual compute resources necessary to make endpoints and nat gateways work?
I assume the hourly charge is because NAT gateways are just EC2 instances, but they should be able to deploy using t4g instances and the monthly costs should be lowered significantly.
The reason for the hourly cost is a bit subtler than that, but we are working on the cost of this stuff.
(Source: Work at AWS.)