Here’s a quick civics quiz. Why did Colorado’s Legislature vote in 2021 to ban plastic shopping bags and polystyrene food containers at most retailers and food vendors?

A. The bags and containers are a source of litter.

B. They take up space in landfills. C. They aren’t entirely biodegradable. D. All of the above.

E. The Legislature isn’t sure. As anyone who has observed Colorado politics a while can tell you, the correct answer is “E.”

(Sorry, there are no extra points for guessing that plastic shopping bags might suffocate lovable sea creatures — otters, perhaps — a common premise of bag bans along the nation’s coasts. There is, of course, no sea creature, or sea, within at least 1,000 miles of Colorado.)

But even if no two members of the General Assembly who supported the measure are likely to agree on the exact reason for their support, they probably will agree that it just felt right. And isn’t that what good policymaking is all about?

As a report in The Gazette reminded us, that policy adopted three years ago is about to take effect in earnest next week. Starting Monday, Colorado stores and retail food establishments will be prohibited from providing single-use plastic carryout bags and polystyrene containers to customers.

It’s part or two-step phase-in that began last Jan. 1, when the retailers by law had to start charging a fee. Now, the bags and containers are going away. Not only at supermarkets but also convenience stores, liquor stores, restaurants, dry cleaners, drug stores, clothing shops — the list goes on.

The many affected retailers have no choice in the matter. They aired their practical concerns when they could, during the 2021 Legislature. Their protests fell on the deaf ears of ruling Democrats, who’ve never met a ban they didn’t embrace.

Which means no more bags for cleaning up after your spaniel’s early morning walk through the park. Nor for the dozens of other uses the bags have had around your house after they hauled your milk, eggs and potatoes home from the market.

No more foam carry-out containers, either, for your chicken sandwich or street tacos. So what if they kept your lunch warm even in the coldest months and then crumpled up to nearly nothing in the trash when you were done?

In other words, it simply doesn’t matter that the bags and containers made a lot of sense and did no discernible harm.

And don’t dare mention how convenient they have been. You’ll be called shortsighted or even selfish — possibly by the very same lawmakers who can’t explain why a ban was necessary in the first place.

They’ll just ask you if you want your children or grandchildren to inherit a world with plastic bags and polystyrene containers. They’re so, you know, artificial! They’re not “sustainably sourced” from “plant-based” byproducts. They’re not derived from something the style sentinels might deem cool. Like hemp, maybe.

So, get used to it. The train has left the station; get on board, or get out of the way. Even though nobody seems to know where the train is going, or why.