If Photoshop managed color is chosen in the Print dialog, the print driver will automatically select Application Managed and prevent you from performing double color management.'
Makes no sense. It should select No Color Management in the driver.
Application or Printer Color Management IN Print (Photoshop) do different things indeed but neither will work correctly unless the actual print driver is set to match what's done in Photoshop.
IF you select Printer Manages Color in Photoshop, the driver can now take over (assuming it, and the OS are all taking the same language). Photoshop hands the data to the driver with a profile, the rest is supposed to happen in the driver itself. At least in theory. Printer Color Management IS supposed to make it easier on the user by letting the data go to the driver and having the driver take over. Unfortunately PMC doesn't always work.
Application Manages Color does the conversions and passes that onto the driver. As far as I know, there is absolutely no communications from Photoshop telling the driver "I managed the color, now set yourself appropriately" although I suppose that's possible and something Adobe would like to work on with support from the printer manufacturers.
But the bit above "If Photoshop manages color, the print driver automatically selects Application Managed Color" isn't at all clear since Application Managed color is an option found directly IN Photoshop.
How often have you and others told users over and over again to turn off COLOUR MANAGEMENT if using LET PHOTOSHOP MANAGE COLOURS? How often are bad prints caused by this simple omission? How much grief and stress does this cause in the digital printing world?
Application Manages color almost always works, Printer Manages color often doesn't. Application Manages color allows the application to handle the conversion, in the case of Adobe, using ACE and BPC. That's not the case with the printer handling this.
My question again: is this a way to make the process easier?
Someday, when its reliable, maybe.