Firstly, RJ45 has a mini interface.

Secondly, the RJ45 is an engineering grade interface that is not comparable to the consumer grade interface USB. Of course, there are also more impressive engineering grade interfaces, such as the aerospace grade. Let's start with MiniRJ45. In my impression, Lenovo and Huawei both have similar products aimed at professional use.

Some people say that there is a difference between this thing and inserting a USB network card. The difference lies in the fact that the MAC address of this thing belongs to the computer, while the MAC address of the USB network card belongs to the USB network card. Many enterprise level applications need to bind MAC addresses, which is such a niche requirement. Not many people buy it, most of them just use WIFI on mobile devices, those using RJ45 don't care about size, and X1's mini network port is more of a show off. I don't care if you need it or not, but others don't.

The effective transmission distance of the network cable is 100 meters, and the speed requirement can be lowered to 200 meters. USB should not be compared to this. RJ45 was born in 1990, more than 30 years ago, and its physical interface has not changed to this day. Unlike in the consumer field, many engineering devices need to be used until the end of their lifespan. Can USB compare to this 30 year consistency?

Another thing is fast speed, 10M in 1990, 100M in 1995, 1G in 2001, and 10G in 2008. So, in the field of network engineering, what can USB compare to RJ45? As for personal mobile devices, either use WIFI or get an adapter.