> Planting a seed 40 years ago may, in part, cause a tree to fall on my house at some point.

Sure, and a butterfly beating it's wings may have lead to JFK's assassination, but there are way more important factors.

> which can be used to circumvent or otherwise avoid the purpose, implied or explicitly stated, of the system

Did you read the law? It explicitly excluded luggage from the tax. Because the tax was never intended to apply to luggage.

So it sounds like the opposite of a loophole, by your definition.

The implied purpose of taxing airline tickets is to collect taxes on flights. As you noted, baggage fees for all bags was not standard practice at the time, nor for decades later. (I wouldn't know where to start with researching the original intent of this carve-out of the law.)

The loophole's theoretical existence and the loophole's widespread usage needn't correspond temporarily for it to be a loophole. If I find a loophole in "don't murder" laws that've been around for 200 years, it's still a loophole if I start offing people with impunity.

(For example: https://en.wikipedia.org/wiki/Zone_of_Death_(Yellowstone) is a potential loophole that existed since 1890, but discovered in 2005, that clearly conflicts with the intent of the Sixth Amendment)

Some airline might try "free ticket if you pay for a bag" style setups at some point, if they're daring enough to risk its being closed as a response.

> The implied purpose of taxing airline tickets is to collect taxes on flights.

Sure, but the people who wrote the law specifically excluded baggage fees along with (looks at law) about a dozen other charges that airline levy.

So how can one argue that it wasn't the intent of the law if it's written plainly in the law?

It's not like the law says "this tax applies to baggage", then airlines created a new definition of baggage and then claimed their fee isn't taxable.

It seems like you use "loophole" as a synonym for "things I don't like but are permitted".

> So how can one argue that it wasn't the intent of the law if it's written plainly in the law?

Again, in this case, that exception seems highly likely to have been crafted to permit a practice common at the time, not a practice that became common 40 years later. You pointed that gap out; you can't have it both ways.

Bills being passed that don't reflect legislative intent is hardly unheard of: https://www.motherjones.com/politics/2022/07/minnesota-legal...

"Here’s something you don’t see every day: On Friday, THC-infused edibles and beverages became legal in the great state of Minnesota, after a law containing the legalization measure was included in a health and human services funding bill. How did this measure get through? Critically, a key Republican state senator who co-chaired the committee that passed it didn’t read the text closely enough."

Or when TN almost accidentally legalized child marriage: https://www.wkrn.com/news/tennessee-politics/a-get-out-of-ja...

> It seems like you use "loophole" as a synonym for "things I don't like but are permitted".

Yes, that's precisely the definition of one. https://en.wikipedia.org/wiki/Loophole "In a loophole, a law addressing a certain issue exists, but can be legally circumvented due to a technical defect in the law, such as a situation where the details are under-specified."