These wholesale carriers know that recipients will flag unsolicited political messages as spam (to the recipient's wireless provider), and they don't want consumer wireless providers to block or heavily rate-limit messages from their phone numbers. The political campaigns cycle through phone numbers, so their unsolicited messages can "taint" many phone numbers - which will affect other customers' campaigns. The wholesale carrier's incentives aren't perfectly aligned with your incentives, but they're not totally different.
The 10DLC cartel wants to fine instances of unsolicited text messaging up to $20,000 per instance, hence why there is a big pushback against registering with this unsanctioned, not FCC mandated organization called The Carrier Registry (TCR).
TCR has been a nightmare to work with for those that do participate in their bureaucracy. You fill out pages of forms with everything from EINs/SSNs to the owners and co-owners of the firm and exact examples of what they plan to text, then 6 months or so later the TCR says "Oh, sucks to be you, we're invalidating all current registered companies, pay $50 to register again and fill out entirely different forms!
Also, T-Mobile is tacking on a new inactivity fee of $xx a month per business if your client doesn't message a T-Mobile number every few days :D"
Keep in mind that sometimes they can skirt the rules by not using automation per se. Instead, they have a bunch of volunteers sit in a room (or online) with special apps that distribute a phone number list (often from NGPVan or the Republican equivalent, forget what it's called) between the individual devices. Then each human has to click "send" or "call". It still gets routed through their VOIP systems, but because there's a human in the loop, it's no longer fully automated... just like 90%, enough to get around the FCC rules.
It's pretty sketch. I went to one of those volunteer parties before I realized that's what they're doing.
Thankfully Google Fi does a really good job at blocking this kind of spam, texts or calls.
So, you should still report it to the sending carrier.
Background: Most larger, reputable US-based wholesale carriers have policies that are similar to the CTIA's guidelines for political campaigns: https://www.ctia.org/news/political-text-messaging-engaging-... . CTIA sets a much higher threshold, including opt-in permission.
This is a bit like the FCC's definition of email spam (a very low bar - what's legal) vs. a mainstream email service provider's terms of use (a much higher bar - what they permit you to send through them).