Can Someone Explain Why I Saw This All Over Long Island Maine?

I thought it was one car being a rebel, but it's on many cars on Long Island.

First, let's break down Long Island. I don't know if I'd ever been to Long Island before, but there's a bakehouse that sounded delicious. Byers & Sons (LO Bakehouse) is open for limited days currently and will move to every day as the season kicks in. I went on a hot summer day last year with a 45-minute Casco Bay Ferry ride (you can take your own boat). I took the ferry. They have yummy food and drinks and of course, baked goods!

The ferry ride was so relaxing and the island is so cute. When you look up Long Island, this is what the town website says:

Long Island, located in Casco Bay, is one of Maine’s 15 islands with year round communities.  The island is 3 miles long and 1 mile wide, and has a winter population of 200, swelling to over 1000 in the summer. In the early 1990’s, when the City of Portland reassessed all of its property and the tax rate tripled on Long Island, islanders decided that local control was the only way to preserve our year round community. On July 1, 1993 the Town of Long Island became the first new town in Maine since 1925.

I remember this! It was a big deal that Long Island left the clutches of Portland. It was also the year I got into morning radio. Anyway, you may also know Long Island for the Long Island lobster boat races! I've seen those and they are wicked fun! But have never actually been on the island.

During the quick walk to the Bakehouse, much like Peaks Island, there are a ton of golf carts and a few cars scattered about. But I kept noticing something very odd.

No license plate, just a bunch of stickers. Wait, what? I thought it was someone being a smart-ass, but it's like this on at least half the cars I saw. What am I missing? I'm pretty sure if I tried this in Portland I'd get pulled over. Is this part of the secession? Somebody help me out.