Paying twice for users?

It would appear that Figma was designed to make collaboration easy, however it seems very expensive to collaborate?

We have an Figma Enterprise License and around 8 users. We work with other agencies and clients. They have Figma licenses of their own.

However when we want to collaborate on a file, we have to pay a full editor licenses fee for each user we want to collaborate with, even though they are already paying for it them selves?

When we want to edit in their files they have to pay for us. I can’t get this to make sense.

Surely Figma is designed to make collaboration easier?