Couldn't agree more on this. Even if finance, sales, marketing or other deps are involved, billing is an engineering thing! Back in 2016, while building the billing system for qonto.com (european fintech unicorn), we were surrounded by people willing to add complexity to a thing they don't understand. A team of 2 engineers building it ended up in a whole squad called "Pricing Cross Functional Team"... even the name of this team was complex :)