Does the lady friend have a bit of OCD? I can't say that the first thing I think about when I travel is having tip envelopes. Must admit that I haven't travelled to developing countries but I do tip. I tip on the quality of the service and I tend to be on the high side but only if warranted.  I've worked as a chambermaid at a Rockies resort while in university and have seen everything. I had an American couple  who were there on holiday and would come by and find me at whichever cabin I was cleaning to say good morning. I found that very touching from someone who was a heart surgery pioneer,: trained Christian Barnard , John Hopkin's board etc. and a health advisor to the President. And yes they were generous in their tip. Of course that was many years ago but I've always been a generous tipper when deserved but don't push others to do the same.

I can't see getting worked up on thinking so far in advance until you see the level of service . It takes the pleasureout of your vacation.