Is applying for visas (for travel) a painful and confusing thing or a simple one? Do you find trouble in trying to find out which visa to apply for and what all documents have to be submitted?

Me and a friend of mine are trying to validate our idea before we build a product. So, if you can spare 5 minutes and fill this form, it will be really useful for us. https://docs.google.com/forms/d/11T1IzkS2ZSWDOCQYAXEUxpDKiRExbUgrb7_k8Zedp1o/viewform

Note: 1. We know that American citizens don't need visas for a lot of countries in the world, so, we are more interested in perspective of non-americans before going forward.