Typography observation

While walking around scouting typography I noticed that a big percentage of signage is uppercase, and almost always a sans-serif instead of a serif. Why is it that? It's cause serif fonts tend to look really clumsy and ugly in uppercase, especially for titles and headlines.

Not bad.

Same font in uppercase. Somehow this doesn't work. Sans-serifs are better suited for large bulks of text.

Really thin sans-serif... mmmm...