Why can't that be scaled down to a few hundred megs of data running through a system, end-to-end, on the local machine?
Not being able to scale down seems like a code smell to me. Is there so much overhead in the microservices that even at idle, or very low usage, they can't even be started?
Again, talking here about the "run the world and click on things" approach vs developing against tests / API schemas / whatnot.
Postgres performance will be different to prod, yes. That's all part of the realism - cost trade off. All models are wrong, some are useful.
The point is that diving headfirst into making matchstick model unit tests is dumb when you could build something to test against at reasonable cost which is a lot more representative of reality.
IMO this is an obvious point if you adopt a cost/benefit approach to development but it's often impossible to see for the dogmatists.
To be honest, short of issuing every developer with their own production-grade environment to debug against I am not sure what exactly would satisfy this line of questioning.