Why wouldn't it? About a 2 dozen RDP clients exists for both Android and iOS.

There's just a lot in new versions of RDP. Audio, printer, and video redirection. Clipboard sharing. WPF effects support. Etc....

Its cool that these Android clients support all this, but I'm surprised.

most require a desktop client to be installed on the other machine - in instances where you have only user permissions on the other machine (work) this becomes troublesome.

I'm not talking about software that needs a server (like VNC); I'm literally talking about clients that talk the Microsoft RDP protocol. There are plenty to choose from for either platforms

Also if your work using something like Citrix; clients exist for both platforms for that as well.

RDP is a protocol implemented directly in dozens of clients in both the Apple app store and Google's play store. No need for installs on the target machine.