You don't need an explicit penalty: if you violate the license, it terminates.
Here's the text of the relevant section of the GPLv3 (the GPLv2 only has an equivalent to the first paragraph):
You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).
However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.
So, on a second violation of the GPLv3, or on a first violation if it takes longer than 30 days, the rightsholder can already say "You need to pay me if you want your rights reinstated."
Conservancy has been using a variant of this tactic: they get a friendly, clear rightsholder for something like Busybox (which has relatively few authors), inform a company that they're violating the GPL and revoking the Busybox license, and demand GPL compliance for all software, including stuff like Linux which has so many authors that getting a clear rightsholder involved is harder, before reinstating the Busybox license.