Our customer needs to set different shipping costs per country. The only shipping module that allows "zoning" is the tiered weight shipping but it does a check for non-zero weight:
We don't really have any use for the weight field and the customer does not want to fill it in for all the products.
If one doesn't want to ship under a certain weight, there is already a min_weight field in zone tiers and you can get the same behavior by not setting it to zero.
I suggest either removing the check or creating a separate Zoned Shipping module.