Although the exact origin of this term isn’t known, it has been in common use since at least the 1960’s and 1970’s. ‘One size fits all’ can be used in either of two ways and the meaning of the phrase doesn’t change, either way, however, the two ways are opposites.
That is to say, if a person says that something is a one size fits all product or situation, it means that there is no difference in the product size and it works for everyone in the same way. If it is stated that it isn’t a one size fits all product or situation, ‘one size fits all’ still means the same thing, but the condition is the opposite.
The meaning of the phrase is quite easy to understand because it means exactly what it sounds like it does. For example, an adjustable baseball cap is a one size fits all cap. The cap itself is the same, regardless of who is wearing it. It is adjustable so it can be used on a head that has a large circumference or one that has a small circumference, but the cap is still the same size, either way.
An example of something that isn’t one size fits all could be the US income tax code. If there was a flat income tax so that everyone had to pay exactly the same percentage of their income, it would be one size fits all. However, the code is graduated so a person who makes more money has to pay a greater percentage toward taxes. This is why the top-earning 5% of the population pay 95% of the taxes, while the bottom-earning 20% pay little or no taxes and might receive money even if they didn’t pay anything. Thus, this couldn’t be construed as something that is one size fits all.
Although this phrase is normally used in connection to an object or service, it can also be applied to thoughts and ideas. So progressive ideas, liberal ideas, and conservative ideas aren’t one size fits all.

No way that conservative morals, values and views fittingly describe the 1 iota liberal and progressive leftist brain cell. There’s not even iota of space and matter for critical thinking and logic.
Exactly. Ideological ideas aren’t one size fits all. Differences occur anytime emotions become involved and some ideologies are virtually based on emotions. That is one reason there is so much division of thought even among those who identify with those emotion-based ideologies.
English is at best hard to learn. American, is what I suspect would be advanced studies of language.
ps the top 5% of Americans pay 58.6 % of income taxes in the US. They earn between 200,000 and many millions per year. You have a mistake, according to the Pew Research 2015 data (2015 is the last published IRS year).
I’m not sure that American English is any more difficult to learn than British English. Both have their own idiosyncrasies, spellings, and so forth, and the slang can be different, but the basic structure of the language is pretty much the same. Certainly, most Brits can understand what an American is saying and the other way around. For many other language-speaking people, though, it is difficult to understand. For one thing, the idea of the noun preceding the verb can be a bit confusing. The adverbs, adjectives, past-participles, and such can also be confusing. Then there are so many words that are spelled the same but pronounced differently, with different meanings, and other words that are spelled differently but pronounced the same.
I feel sorry for people who are learning English, particularly if they aren’t proficient with their own language. However, I also admire anyone who can speak more than one language, especially if they speak each language fluently.
Ohh wow, That’s is Interesting… Nice Post.
Easy to shop when one size fits all. Reminds me of growing up in Brooklyn where kids picked up the oddest things like knowing what is Brooklyn talk or also slang so there was a running joke. Where are you going? To toidy toid street and toid avenue translated in proper English 33rd Street and 3rd Avenue but that is not Brooklinese.
LOL…and I imagine many Neww Yawkas would understand that
You will never really retire, because your nature is to teach – your writing proves that.
You are probably right and I thank you for the compliment. However, there is a difference between being officially retired and honestly retired.
This is great Rex. Imagine how so many of our connections on here feel about our language. Very confused.
I have little doubt that most people who don’t have English as a first language are confused by it. For that matter, a large number of people who are native English speakers are also confused by the language. Part of that has to do with the number of words from other languages that English absorbs.
That is interesting… I didn’t know its a slang… lol
thought its some idioms … oops
It is actually a little of both, to give a one size fits all answer. lol
Thank you very much for precision teaching, outside of the English speaking area, and that helps us to understand better.
you are quite welcome. That is part of my goal; to make it easier for people outside the English speaking world to understand what is meant.
Thank you very much.
I’m glad that the wars of this kind help.