Term for a small number of bad incidents ruining something larger for everyone else?

Question

I'm looking for a word or expression that describes the following types of events / patterns.

Example 1: Until the late 1960s / early 1970s in the USA, airport security was minimal and you could board a plane casually just like a bus or train. But after a series of skyjackings security was increased.

Example 2: Computers used to be very permissive in how software could operate. But sometimes badly designed or malfunctioning programs would cause serious problems; so operating systems have become much more restrictive. As a result we now have many more layers of user prompts, passwords, etc. to try and avoid this, even though most individual actions are probably not going to be problems.

In both of these cases a relatively small number of bad 'actors' have caused events which now require 100% of people to deal with tedious scrutiny & restrictions. In that sense something which was once free & easy has now been "spoiled" for everyone, apparently forever, because of these few bad cases. Is there a succinct word or turn of phrase with that meaning?

Answer 1

There is a very well known idiom to the effect of one bad apple spoils the whole bunch, which is also referenced in Cartoon-Illustrated Metaphors: Idioms, Proverbs, Cliches and Slang by Kaimen Lee Ph.D. as One Rotten Apple Spoils the Barrel. The Random House Dictionary of America's Popular Proverbs and Sayings lists it under The Rotten Apple Spoils the Barrel.

One bad person can make everyone he's associated with look bad. The proverb has been traced back to 1340 and is similar to the latin: Pomum compunctum cito corrumpit sibi junctum ("A rotten apple quickly infects its neighbor"). […] The proverb is found in varying forms. The word bad is often used in place of rotten, the words box, bushel, its companions (neighbors), his companion (neighbor, fellow) are used in place of barrel, the words "destroys and injures are used in place of spoils. The saying is often shortened to "a bad apple* or bad apples.

The malleability of the phrase suggests to me that so you could say "a few bad apples spoiled the whole bunch" to pluralize it. This is corraborated by the following Google ngrams chart, which suggests that the plural form may be more popular:

The bad actor aspect is best exemplified by the Collins Cobuild Advanced English Dictionary 1st edition (©2015), which defines the term rotten apple as meaning:

You can use rotten apple to talk about a person who is dishonest and therefore causes a lot of problems for the group or organization they belong to.

Also take note of how it mentions "causing problems for the group or organization", so if one person's bad actions is causing problems for the rest of the group. In your example, the dangerous passengers and tech illiterate users have added to the inconveniences of the safe and savvy members of those categorical groups with the precautions taken against everybody.

I think the best way to exemplify it is the variant "don't let one bad apple spoil the whole bunch", which adds an element of futurity to it. This is exemplified in the title of an article called Please don't let one sour apple spoil the whole bunch written by Vivian Li of Deerfield Beach High School for South Florida SunSentinal on September 22nd 1999, although the contents of that article are not especially noteworthy for this context.

An example of this phrase possibly being more abstractly applied to experiences can be found in 180 Days of Beautiful Truth: When You Change Your Mind, You Change Your Life by Sparkle R. Sanders:

Day 155

And no, not every person is like that. That's just who you know. Today, don't let one bad apple spoil the whole bunch. Don't let one bad experience generalize and settle for just "anything."

It is a little hard to tell here since the phrase could be refering to the person in the first sentence, or the experience in the following sentence, but I do believe the aspect of futurity suggests more strongly that there is some amount of promise to be had, that you might not get if you let the past experience spoil future events.