To find out the shutter count, you have to download third-party software which either interrogates or alters your camera firmware and who knows if it actually works or introduces bugs/virus, or in the worse scenario, turns your camera into an expensive brick. To have the shutter count on the camera menu is a convenient and simple thing to do like having the odometer on the car dashboard. Why don't camera manufacturers bother to do it?
Knowing the shutter count is only useful in two situations:
- for repair, which is handled by the manufacturer. There's no need to make this a public feature.
- for selling/buying used gear, which the manufacturer has low interest in. They build cameras to sell them, not to simplify the process of reselling them.
The manufacturer has no (big) benefit of creating that feature for the used gear market. Other features are more desirable by the customers that buy new cameras, which is what the manufacturer makes money with.