Depends. Depends on the country, the airline, the airport...
I've recently flown on airlines where it's all manual, no choice (NZ ex-LHR) where you can check yourself in, but all luggage is manual (BA ex-LHR), where you can check yourself in, print off a baggage tag, then show your BP and passport to drop it off (SK ex-OSL) and where everything is automated and you can drop your bag off yourself (OS ex-VIE).
Probably a combination of demand, regulations and 'security'.