Probably because the brand recognition on a pair of jeans is too low to even bother. A logo on a shirt is instantly recognizable: it's right in front of you. P

Probably because the brand recognition on a pair of jeans is too low to even bother. A logo on a shirt is instantly recognizable: it's right in front of you. Putting the company name on a jeans only works for short names. Even a relatively short name like Facebook is challenging to keep it readable from a short distance, let alone from a few meters. Similar for logos, with the additional challenge of logo placement. Where will you put the logo on a jeans? On the back? That will cause a lot of uncomfortable situations. On the front? Now you have to look down in front of the person wearing the trousers, making it even more uncomfortable. Maybe jeans in the exact company color could work, but you need a lot of different sizes. People are very picky about the fitting of a jeans, so you'll end up with a huge number of sizing combinations. Shirts a far more easy: from XS to XL and you're done.