> Sure, it cost me £6/mo to serve ONE lambda on AWS (and perhaps 500 requests per month)

I went on pricing calculator, and to arrive at $6/mo with only 500 requests, you'd need to run the lambda for 15 minutes with 2Gb of RAM.

On the other hand, we have dozens production workloads on Lambda handling thousands of requests daily and we spend like $50/mo on Lambda.

I'm really intrigued by what you did to get to those figures!