Why don't touchpads have scroll wheels?

Question

I was using Google Maps on my laptop today and a question occurred to me: why doesn't the touchpad have a scroll wheel next to it? There's a ton of wasted space each side of the touchpad so space isn't an issue, and the touchpad is generally there to give the functions on a mouse. It has 2 buttons, but most mice also have some kind of scroll wheel, so why isn't there one next to touchpads? It would make it much easier to perform many functions on laptops. It could even be clickable to double as the middle mouse button, which would be super useful.

Answer 1

Many laptops DO have left/right and/or up/down scroll capability using the touchpad. This functionality is often identified by a different colour line on the touchpad showing the user where the scroll portion is.

An example image:

Answer 2

In addition to the scroll-sensitive area on the side and bottom of many touchpads (which isn't always marked, so you might have it even if there isn't that line there), newer laptops generally have smartphone-style multitouch gestures, so you can use two fingers to scroll (just swipe up, down, left, or right with two fingers), as well as using pinch to zoom. For two-finger scrolling, the vast majority of laptops I've seen made in the past few years have supported it; it's more surprising if it doesn't work.