If you are concerned about maintaining access to the international post system for poor people, how is this change going to help?

Surely it does the opposite - someone living in the poorest country in world would have to pay rich-European country rates to access their postage system.

Btw. I strongly suspect that the international rules on charging for postage were chosen for simplicity of implementation and not out of a sense of altruism for people in poor countries.

How usual is it sending hand written letters in 2020? Even in poor countries, I believe people sending hand written letters across the world is very uncommon.

If you believe it's still neccessary to keep sending letters across the world a neccessity, well, then we could only allow thin letters that can not hold anything else than a written letter - no items, what so ever.

I didn't mention hand-written letters at all so I've no idea why you're asking that question.

Your original message seemed to express concern that the original purpose of the rules for international shipping was to support people in poorer countries?

If this cross-subsidisation is removed, then people in poorer countries will pay more and people in richer countries will pay less to send stuff to each other. That's simple arithmetic.

And I was wondering how someone could simultaneously support such a policy while expressing concern about access to international post in poorer countries.

Sure, you didn't mention hand-written letters, but hand-written letters is exactly what the agreement/law (in europe) was designed to take care of.[0] So I think you are missing my point.

It was definetly not designed to be abused by the world's biggest companies to be able to ship stuff for near zero cost world-wide. If you can't see how it's clearly being abused, I don't know what to say.

A trade union created in the late 1800's that made sense then, may need a change now. Although alot of damage is already made.

[0] https://en.wikipedia.org/wiki/Universal_Postal_Union

It is not about being handwritten or not, in many situations physical letters have a different legal weight than other mediums.

I agree, I meant to write physical letters. And if it's of legal weight, they should be able to afford shipping.

The problem is not physical letters, it's the postage of goods across the world, being cheaper because of subsizidies.