We had this issue at juicer.io where all of our EU customers (and some others) needed to have their VAT numbers on their invoices so they could submit them for reimbursement, but at the time we were just using the built in Stripe receipts.
Unfortunately they didn't allow you to customize them at the time so we were creating these invoices by hand. We would set up a monthly calendar reminder to create the invoice manually from a terrible template, then we'd send it off.
That worked okay for a while when we only had a few customers, but as Juicer grew, so did the amount of invoices we had to customize and send (they compounded in fact!)
Eventually it got to be several (extremely boring) hours of work every day creating these invoices so we decided to start looking for a product that would do it for us.
We wanted something simple, that would connect to our stripe account automatically, and just allow us to add custom fields to each customer and send them their invoice every month. Unfortunately there weren't any products doing this as far as we could tell. So we did what any person here would do: we made it ourselves.