Why are phone service providers against companies like iNum making use of the +883 and +888 global country code for international numbers?

This sounds like it may be the future of voice communications. Where country and area codes are replaced by a universal number that is just a number. Problem is that country codes and area codes are good for the telecommunication industry. Charging for long distance and international calls keeps the cash flow going. So it is not really that big a surprise that there is resistance to a global number.
More practically, there are subtle but important differences between infrastructures depending on where you are globally. Having a single number tied to a single device that allows you to travel globally means building a device that can not just transit countries, but can transit infrastructure as well. I imagine that would be cost prohibitive (considering what they are already getting for a mobile device these days).
Maybe time to go backwards. Get john's phone, prepaid wireless, and keep a little black book.

http://www.johnsphones.com/store/item9

Definitely getting annoyed with the high costs of having a cell phone.

If this service had to pay taxes and inter connect fees they could not offer the service. They don't guarantee a level of service, you get what you pay for.