We don't even know what this 1€/instance is paid for: the only source we have is a tweet from the OVH founder. Maybe there was a discussion before, or maybe not, we're just speculating here.
My guess is the price is for certifying the images, which also means guaranteeing the kernel has all the security patches in it. That means OVH would be able to customize the kernel to integrate it in their control panel, and the customers would get a secure and not broken Ubuntu image.
The other option is to ship the stock image (and maybe put the integration in a .deb, as another person suggested here), and don't pay anything because you would be OK under the trademark policy.
What's a better way for Ubuntu to do that? Given the open-source nature of the product, the trademark is the one avenue they have, and it's reputation quite important to differentiate themselves.
My point is that perhaps trade mark/copyright law isn't the best way to encourage vendors to update their products.