Why?

Why do printers and such have DISKS that need to go into your computer to make them compatible?
That makes no sense to me.
I should be able to plug my printer into my laptop and click "Scan" or "Print" and the printer says to me, "Yes m'am! As you wish."
Someone please tell me that my printer is from the dark ages and this is how it works now.
Otherwise I'm going into so sort of business here.