Not sure how or why you would get into a discussion with some stranger about whether he upgraded his horse, but... either he was lying about not upgrading, or you are experiencing some bug. I would assume the former.
The Imperial mount starts with a 15% speed boost and, just like you, they can upgrade their speed 1% per day. You have only upgraded our speed 10 times, while they could have upgraded their speed 20 times, or more, since release. It is very possible, and highly likely, that they are at the same, or even higher, speed than you.
The difference will come at the cap. The Imperial horse's max speed will cap lower than yours.
Really, is that right? Upgrading the horse's speed only makes you Sprint faster?randomriffyrocksprerb18_ESO wrote: »It only affects sprinting so far