Unattainable Triangles are simplified diagrams of three attributes where at most only two of the three are possible. It’s a good way to frame choices.
Here’s “unattainable triangle” of quality, service and price. It looks like this:

The concept is that as a consumer you can opt for two of the three factors above, but not all three. You can’t get great service, a high quality product and a low price all at the same time. Something has to give! Sometimes you only get one!
Think of owning a luxury car like a BMW or Mercedes. You get great service at their dealerships, a very high quality car but its not cheap!
Another way to express this unattainable triangle is as follows with service replaced with speed or time:

Thus, you can have something:
- FAST & CHEAP but it won’t be good quality
- CHEAP & GOOD QUALITY, but it won’t be quick or on time
- ON TIME and GOOD QUALITY but it cannot be CHEAP
For example:
- Starbucks is quick and high quality but it is not cheap
- McDonalds is quick and cheap but of low quality
- The U.S. Postal service is cheap and high quality but is slow
Why is this the case? Higher quality products and services take more time or money to produce. Producing something quickly will be expensive or of low quality. etc.
Here are some other fun unattainable triangles where you can at best have two of the three:
Here are the choices facing those in college:

These choices concerning jobs are especially true in the financial industry:

With respect to dating:

Parenting toddlers:

Here are choices faced by high-school males:

Food choices:

This triangle was proposed in the context of entrepreneurs:

This is the usual trade-off for those buying a house:

Finally, this one seemed pretty spot-on:

Post office – high quality?
It’s slow but stuff gets where it’s supposed to go nearly 100% of the time.
That’s true for Swiss national post. They have 100% satisfaction rate.
https://www.statista.com/statistics/1178668/countries-best-postal-services-worldwide/
In medicine:
Perfect, immediate, and free.
Liquid, high yield, secure
Love it! So true
I have always used the triangle of :
Cheap, Fast, or Perfect (or as to perfect add possible).
In my remodeling business. I try to keep that in perspective when dealing with other businesses also.
I just met your wife yesterday and I have to say it would appear you beat the dating triangle – having clearly achieved all three! As did I with my husband 🙂