The majority of espresso enthusiasts are looking for a few different things...
1) Flat burr (instead of conical). It has gone back and forth over the years, but consensus now is flat burr grinders produce the most desired flavors for espresso. The bigger the burrs, typically the better - more clarity etc.
2) Low retention. Most coffee nuts want to put x grams of coffee into their grinder, and get exactly x out, without leaving any behind to get stale etc. A coffee shop where they are pulling hundreds of shots a day does not have to worry about this, but home use creates poor workflow.
3) Single dosing. Again, most enthusiasts keep their beans in airtight containers, or pre-measure into smaller bean tubes, and also might have 3-4 different beans as well (couple origins, a decaf etc), so they want a grinder WITHOUT a hopper so they can dump in their desired bean of the day, grind it, and drink it. Then, perhaps change bean to a different one to pull a different type...having a grinder that does not single dose makes this very annoying.
Luckily, there are a bunch of newer, lower cost grinders recently hitting the market in the last year or so that try to meet all these...this one seems to be one of the better "Under 500" ones... Turin DF64 Gen 2. These lower cost flat burr grinders typically use burrs around 64mm. Note, some grinders let you choose different burrs at the time of purchase- some more "general purpose", some more for espresso etc. Drip coffee is far less demanding on a grinder.
That said, if you have the budget (talking into the $2k market) there are a few larger, flat burr grinders that are on the elite level. I'll never have one unfortunately. They use burrs in the 83mm - 100mm range, and are built for lifetime use....these are hand down to your grandkid kinda grinders.