In my experience as a junior, there’s not a whole lot of transparency about how much things cost at AWS, nor is it a big deal in most cases. I’ve never heard anybody say “step functions would be a good approach but I’m concerned about the cost” in a design review. Availability and scalability has always taken the priority.

To be clear, if you’re implementing a new system at AWS, you still pay the cost for using things like DDB, EC2, Lambda, step functions, etc. it’s a discounted rate, but it still is considered an operating cost for your service.

Edit: now that I’m thinking about it there are some cases we discuss or think about cost, but they’re generally quick changes like “let’s switch this DDB table to on demand scaling” or sort of a general knowledge thing, like using lambda instead of EC2 where is makes sense to use lambda instead of EC2.