[oldE]

Sugarwood,

There is more than a grain of truth in the diagram above.
These days we have torque converters which lock up faster to minimize slippage.
The torque converter must provide some slippage when starting off so the engine does not stall, but at higher RPMs tends to provide a greater percentage of power to the gears.
The inefficiencies of the older autoboxes and torque converters are the problem unless you have great amounts of torque delivered by the engine.

A lot of the tendencies of automatics to shift at inopportune times can be worked around with some pre-planning and careful footwork, but as pointed out, a manual transmission is easier to control.

Best of luck with your friend.
Les