When you call tech support for a certain piece of software or hardware sometimes the call center people will remote your computer. How do they do this without any type of software beyond windows remote desktop? I have a lot of problems with Windows Remote because it barely works on anything from any of the PC's I use. Teamviewer works fine, but Windows Remote Desktop just sucks.
How do they do it without the customer having to change a bunch of stuff?
I highly doubt that they CAN do it automatically. There are a few possibilities
1) Customer has bought the PC off them in the first place, and some kind of remote control software, such as a Citrix one, or one of other hundreds was already installed
2) They ask the customer to visit a site and the site automatically prompts to install the software. This is very common with citrix clients
3) remote desktop IS awful, but does work well when the stars are all aligned and earth and mars line up with the 3rd moon of jupiter
You will find they all do install software you may just not realize it because it is not "installed" in the microsoft sense of the word. A lot of these tools use activex or java based things that are only "installed" into memory. There are a large number of these products on the market but most you must run though a central server so allow connections though firewalls and proxy servers. Firewalls and proxy servers tend to make it almost impossible to run remote desktop to solve this issue.