Well, those folks had to spend a few years planning, take flying lessons, dry run everything a few times, and then pull off the most complicated and coordinated terrorist attack in US history.

The actual bomb planning for the Oklahoma City bombing was less than a year and involved two people. So, seems like the bar was raised quite a bit.

Do you think that the bar was raised a bit or that the 9/11 terrorists set their sights a little higher?

You're giving the 9/11 terrorists far too much credit. They were supported/financed by the Saudis[0] and America dropping the ball was the only reason they succeeded.

It's not so much a big victory for the terrorists as a big black eye for America and our intelligence agencies.

One of the 9/11 pilots was reported to Federal agencies multiple times[1] and the hijacking still took place.

[0]https://theintercept.com/2021/09/11/september-11-saudi-arabi...

[1]https://abcnews.go.com/US/story?id=91659&page=1

It prevented 7/15 pretty damn well

7/15: Never Remember

How well did laws to stop isolated crazy people killing lots of people stop … um … a group of countries investing large amounts of money and years of time into planning and training for the largest single attack on a civilian target in history?

I mean sure, you could also ask how laws against shoplifting fail to stop bank robberies, and it would be just as coherent.

largest single attack on a civilian target in history?

Japan would like to have a word with you.

Perhaps "largest single attack on a civilian target by a non-state actor" would be more accurate.

Survivorship bias. You don't know how many plots were prevented by making it difficult to obtain explosive precursors.