I would like to understand why in the popular language when referring to espresso , most people immediately think of a very dark roasted coffee. I have even seen the words  espresso roast in some packages.
It would be good to review the definitions of connoisseurs about what is an espresso …

Example: Espresso also called espreso or express coffee, is a beverage that is made in a professional equipment with a pressure of about 9 bars , forcing the hot water thru and around the coffee grounds , obtaining about an ounce or 30 milliliters drink in a period of between 25 and 30 seconds.

What happened to the part where the article should talk about the degree of roast?

The truth is that it does not matter, because you can prepare an espresso with any coffee and roasting. Of course depending on several factors such as the type of machine, pump pressure, water temperature, grinding, tamping and of course the degree of roast, this drink can change, making it stronger or softer, over or under extracted. But that is part of the preparation.

An espresso is the drink that lets you taste, feel, discover, analyze, and to live the true characteristics of a coffee. While it is true that some countries have used blends or mixes to balance the general profile of a cup with complementing deficiencies of a coffee with the features of another, it is also true that tasting an espresso from a particular farm or what connoisseurs called single origin , is a great way to drink coffee. Roasting coffee dark is a very good way to hide defects. This in turn makes it stronger and bitter. So why give a dark roast to a coffee with no or very few defects?
The idea is not to hide anything. The idea is to highlight qualities. Be adventurous and try medium roast and single origin espressos. You’ll be amazed filling the sweetness aromas and flavors of good coffee and contrary to what some people think it will have body and crema.