Seattle had to close one of its largest and busiest bridges this year without notice due to potentially immenent collapse. The bridge was finished in 1984 and was supposed to last 100 years.

Apparently we haven't been good at building bridges for a long time.

https://en.m.wikipedia.org/wiki/West_Seattle_Bridge

If you are talking about the FIU pedestrian bridge, that was not a situation of slow building.

That project was to be a showpiece in FIU accelerated bridge construction (https://www.chronicle.com/article/engineer-connects-his-rese...).

I have not kept up with all the analysis(https://www.eng-tips.com/viewthread.cfm?qid=459940) but IIRC the combination of the accelerated construction, the new concrete truss design as well as organizational changes that left key position unfilled were the major design factors.

There were also clear warning signs of the impending collapse that were ignored.

EDIT: I mistakenly named the wrong university FSU -> FIU