I was asked to write an invoicing system. I know a _lot_ about invoicing systems. The owners who employ me were very explicit: all figures this invoicing system displays must exclude gst/vat. That made sense to them, because gst/vat just confuses their profit figures.

However, the whole point point of an invoice is to communicate to the customer what they will be paying and why. The customers in this case are retail. They are interested in only one figure: what comes out of their bank account. That figure includes gst/vat of course.

As part of this I asked to see what they were doing now. The old system they were using did adhere to their edict: everything was ex gst/vat. As a consequence every person who customer facing (ie, the the vast majority of the employees) carried a calculator to convert the figures to what the customer wanted as they spoke with them. It looked difficult to me, but evidently madly stabbing calculator buttons while maintaining a smooth flow of conversation must be a skill most people can acquire.

This was insanity of course: we could save the bulk of the organisation time and considerable fustraton by just giving these people the figures they needed. So I very explicitly ignored their direct instructions. Note: I had to ignore it, as I had already lost the argument. In due course it was rolled out for testing. I went down a month or two later. The calculators were gone, people were expressing their gratitude. Not a word was said by my managers, and I duly been rewarded every year with raises.

I am an professional. I am hired very explicitly because I know far more about computer systems than the people who hire me. Like a doctor who refuses to prescribe opioid's, I view as my duty to steer them them in the right direction even when they don't want to be steered. If that requires putting my balls on the line and refusing to budge, so be it. They can always fire me if I've made a grave error.