I just watched https://youtube.com/watch/... - towards the (very) end he's talking about how software developers rule the world... and I just realized something.

A while back, I was working on an accounting sub system for a SaaS product. We managed some of the revenue of our customers and had the accounting for that part as well. Revenue + Payments (with all the VAT / sales tax / ... that you need to have). BUT no expenses.

One day, the head accountant of a customer, angrily demanded that we immediately implement a new payment method, called commission.

You don't need to be an accounting expert for knowing, that a commission is an expense you have because somebody else marketed / sold your product / service for you. Making it a payment method is probably wrong. With a bit more knowledge you'd know that the taxes which are around expenses are completely different to revenue or payments. (btw payments didn't even have any taxes in those countries that we covered at that time at least).

So there I was standing, a software developer, trying to explain the product manager and the head accountant of our customer, that the idea is beyond stupid, and the fact that it comes from an accountant is super scary to me. (he was usually extremely picky about everything we did.)

Luckily, it was easy to convince the manager. He tried to explain it to the accountant but that person just didn't get it.

as if designing resilient distributed systems, which have 99,99% up time weren't hard enough, we also need to be experts in every domain that we have to deal with? And if there is a tiny bug and one out of 10s of thousands of transactions is screwed up, people start panicking and "loose trust in the product"? - what the hell is wrong with them?

Luckily it's a minority of customers only, but each of them is such a pain. Do you also have customers like that? who should know better, but somehow you are the expert in their domain?