You have to opt in and there can't be a penalty for opting out, the fact sheet says. That said, there may be a bonus for opting in — perks or whatnot. That will have to be settled separately, probably.
They probably can't advertise service as $49.95, then add an additional $20 charge if you opt-in to the privacy plan.
They probably would need to at minimum advertise both prices in their marketing copy.
probably not a viable option because a VPN offers complete privacy from the ISP, and only costs $5/month.
Why is it hard for the majority of users to use a password manager?
Because most people on the planet are busy and don't give a damn.
It also takes a few minutes to change your smoke-detector batteries...
I'm not sure how you de-incentivise something like that.