Actually, yes. I was deeply involved in the transition of two shelters going from kill to no-kill and moderately involved with two others. I was active in the AR (AR not AW) movement for over three decades. I've done more AR work than I can even remember some days.
As for "absolute facts", it only takes a modicum of research and common sense to understand that it doesn't take seven years to stop using plastic bags.
I've seen no evidence that "resistance" affects the discontinued use of plastics. Moreover, I'm not aware of protests or boycotts to keep plastic bags. If I've missed something, I'd appreciate links to news articles. I just did a quick search and found nothing. (And unless you've lived for some time here in Florida, don't be so sure that you know what it's like here.)
I don't think "resistance" should even be considered. People resist change all the time and once it's done (assuming it's good change), it's done, and people adjust to the new. If people love their plastic bags, then let them hoard them and reuse them in perpetuity.
Plastic bags aren't an issue since no stores in my area are planning to do away with them. We do have an Aldi, but transitioning isn't an issue there. But, as I said, it takes only a modicum of common sense to know that it doesn't take seven years.
As for shelters... In my experience, I've never heard a reasonable or sensible answer when asked why they take several years to go from kill to no-kill. Money is often cited, but when presented with plans to better use their current budgets to shift from kill to no-kill, they just give non-answers, redirect the topic, or end communication.