Like US soccer teams with "United" in their names.

This is actually a Sans font though, the E with serifs is a different font, an older one called Snellen.

(they could make a Serif variant based on Snellen instead of on Sloan)

It's pretty common to distinguish your font from others with a description in the name, be it sans/serif/slab/mono/condensed/extended, etc — it does communicate "this is a font" clearly but it's also useful when you're in an application just looking at a text list of font names.