Chesterton’s fence is mentioned several times here and it’s a good heuristic to avoid the issue. The issue is called the Preparedness Paradox https://en.wikipedia.org/wiki/Preparedness_paradox

The concept you are describing is stopping preventative maintenance and discovering the consequences of said. I just don’t have a word for it.

Chesterton’s fence

From a parable by G.K. Chesterton, suggesting that one should not remove a fence until one learns why it was erected in the first place.

https://en.wiktionary.org/wiki/Chesterton's_fence

The thing with the witch sounds more like mafiosi protection money.
She sells you the circle, and if you don’t pay, she casts summon goblins on your house

hubris

In software development this is called a regression, and it is why we have regression tests. If you don’t run or check the regression tests, the problems they’re testing for can (and do) come back.

“Complacency” is a related idea but a bit more general.

In 2013 Ruth Bader Ginsburg made a famous analogy about the US Supreme Court gutting the voting rights act. She said it’s like “throwing away your umbrella in a rainstorm because you are not getting wet.” That comes pretty close to your sentiment, OP.

survivorship bias preceding confirmation bias? i think this what you were looking for. for example, survivorship happens first because, antibiotics work on bacterial infection, the infection dies down and backed by science, and personal accounts, then cofirmation bias sets, you are getting better, so you stop the antibiotics prematurely because you cant be still “infected”. the infection comes roaring back, now immune to antibiotics, person blames the doctor/Rx or hospital for giving them useless meds. you can apply the same to all the other 4 situations.

i think 1 is different, theres an intentional motivation to do it, the food companies have to pay alot more to sanatize thier food, if they eliminate it, then they dont have to spend so much time doing it. 2)is also intentional, the company cuts corner, they are aware of breaches(baking it into thier profits)

3,4,5 all fits with surviorship bias preceding confirmation bias.

I recommend this podcast episode on the subject: https://timharford.com/2022/08/cautionary-tales-south-pole-race-3/

The best existing phrase I have is, “Dropping your guard.”

It doesn’t necessarily imply anything about why you dropped your guard, and only slightly implies that the bad thing happened while your guard was down.

We could coin a new phrase here by brainstorming. I’ll start:

Fumbled the shield

Chesterton’s Fence is the first thing that comes to mind

Like God said to Bender in Futurama “When you do things right, people won’t be sure you’ve done anything at all”. I propose calling this Bender’s Paradox.

FAFO

Historical Recurrence

The gremlins always return. That’s why the magic witch offers an annual subscription plan, to protect your investment from up to two types of folklore creatures, ranging from classical antiquity to the early modern period.