Having to pay for RHEL services does not mean that the commercial binaries they distribute are (copyright) restricted. If there is a restriction, it centres around the use of trademarks (at least from a casual read of their licence terms).

Canonical on the other hand appear to be trying to restrict the use of their software by applying copyright law to their binaries. They explicitly say in their "intellectual property policy" that you can only redistribute Ubuntu where there has been no modification to it (then later that modified versions must not only remove trademarks, but must be recompiled).