cons: significantly more expensive, don’t work in total darkness, don’t catch attention

freedom of expression does also matter, how much more distracting is this compared to if it was made with retroreflectors? Could these lights be confused for hazards? Is this any different than having a glowing “taxi” sign on a taxi?

yes, you can, and I would expect an “ad-free” service to do so, at minimum replace it with a “commercial break” sign and preferably adding extra commentary.