As the commenter you’re responding to said, just add the cable company to your contacts and the refund is automatic. Opt out of any emails from them other than billing notices.
No, people don't want to pollute their contacts listing by adding every company they have a billing relationship as a new entry to "manage spam". It's visual pollution to have "Comcast" as a useless entry alphabetically in between "Charlie" and "David" just to offset a new spam rebate scheme because Comcast is abusing the law. And if Comcast has multiple identities such as creating "Comcast Updates" and "Comcast New Channels", etc to further abuse the spam rebate scheme for more customer "engagement", you're doing even more digital housekeeping and adding more entries to the contacts listing.
Another problem is that the smartphone's "contacts listing" is a special area that has downstream interactions with other smartphone settings to manage/filter notifications and sounds. E.g. "silence notifications not in contact listing" or "block calls not in contact listing". By adding Comcast into the contacts listing, they can become even more invasive in your life by polluting alerts on your home screen and making your phone ring.
The spam rebate idea can have some weird unintended side effects if such a scheme (or law) is not crafted carefully to prohibit abuse and make life worse.
I'd argue strongly against your premise: people specifically do want to note their established vendor relationships (subscription services, doctors' offices, schools, government services, utilities) if only so that they can distinguish legitimate from illegitimate contact attempts, but also to manage different groups of known contacts differently.
This presumes a few advances, such as reliable caller-ID systems (this is presently not the case for North Amercian dialing systems). Friends who are innundated with robocalls noted that they'd received a call spoofing an entity with whom they do have a relationship, however it was clear from the call characteristics that it was not a legitimate call --- among other factors, the caller identified themselves as being from a different entity, which is a pretty low bar.
The problem of mega-services (financial, comms, federal government, etc.) being subject to spoofing simply because so many people have interactions / relationships with them is an extant problem. But odds are pretty good that your local water / sewer / trash / gas / electric service will be less universal, and knowing that they're calling when they do in fact call is useful.
It seems you're associating a contacts list with a friends list. That's not the case. Your contacts are, well, your contacts, and different contacts have different roles. Among other factors, you might set, say, different contact rules, priorities, and ringtones for, say, immediate family, work, casual social contacts, and business entities. The latter would generally not be permitted to call outside regular business hours, and you might specifically restrict them around mealtimes or other inconvenient times of day (redirecting to voicemail or another messaging service, say).
It would be simple to have a ‘whitelist’ for contacts that are free but low priority and get muted, put in a special folder, or auto deleted. It’s cold contacts from anonymous senders that are impossible to reliably auto screen.
Email providers/phone should have hierarchical contact lists. Comcast can go in the lowest rung, maybe call it subscription services, and your spouse is in the highest rung, in the family group. Each rung comes with its own abilities with respect to notifications, calls, sounds, etc. Have a button at the bottom of every email to add the sender to a group if not already there, and that would handle your spam rebate scheme automatically.
