Actually, quite common.
Many, if not most, commuter and transport category aircraft will approach with power but slowly reduce to idle during the flare, the intent being to touchdown as you reach idle, assuming the conditions allow for it. The automation that Donkey497 speaks of is spoilers and other lift dump devices. I've also never heard of auto-reverse, but who knows - way too many types to say it doesn't exist somewhere.
But, once the wheels touch down its a simple matter of engaging the thrust reverse - be it jets or propellers. If the aircraft was landed at idle this is relatively quick (no more than a second or so to get the process started).
If the aircraft was not landed at idle there will be a delay. Considering a little bit of power is often used to "cushion" the landing, this is probably why you've not seen it a lot.
Now, depending on engine and aircraft configuration, there can be a bit of a pitch change when reverse is engaged prior to nose wheel touchdown, so it does need to be managed properly; but, it's actually easy to do once you get the hang of it for your specific type.