The first part is easy, color code the ticket (e.g. first red, then blue, etc). The second issue is trickier, but it happens now anyway. I would say that they already know how to handle it.
Also, what percentage of the populations color blind? You'd have people boarding for red when green was called, etc. Letters give us 26 possible boarding stages. Even without keeping accessibility is mind, you'd only be able to reliably use, what, %w{red blue green yellow orange}? Purple is out -- too ambiguous.
So yeah, no color codes. Have I beaten it to death enough?
Regarding color blindness, you can also print the name of the color on the ticket. Or increase contrast:
"What can be done to avoid confusion? Most sources on usability and interface design suggest avoid relying on color coding exclusively. Always provide an additional cue; don't rely on color alone. For example, the standard default web browser of a link is underlined blue lettering. Interestingly, this particular color coding would stand up quite well, even without the additional cue of the underline, since blue is the universally recognizable color.
A second way to counteract color deficiency confusions is to make sure that colors have a high degree of contrast with each other."
There are a lot of guidelines and protocols for managing user color blindness in interfaces... it's generally not a sufficient reason to completely avoid the use of color in all cases.
Colour coding the ticket is not trivial - current monochrome printing is easy with thermals. Ever run a colour printer in an office? It's a nightmare to manage just in an of itself. Then there's a lot of investement in creating a system that works across all models of planes. It's doable, but it's not trivial.
Then on top of that is the issue that despite all this, a lot of people ignore what's on the tickets anyway and board when they feel like - the boarding crew are not going to tell someone to go back against the surging crowd and wait their turn. I've been on four international flights before and I followed the "people in this block, board now" - and when I entered, pretty much every time I passed by an uncalled block, it was at least a quarter full. People aren't disinterested particles.
Given also that planes are sitting around doing things both before and frequently after passengers have boarded (or waiting for the late passenger...), I don't think a straight-out claim that 10 minutes shaved off boarding times is a direct 10 minutes shaved off turnaround times (not that the article claims this, just being wary of it)
The video shows an "aisle management" technique, but it isn't a "boarding" technique, as the latter task is much more than wandering down the aisle.
You don't have to print the colors, you can have pre-printed tickets in two colors and have two printers at the checkin counter (likely much cheaper in ink, too, and much better-looking).
The airlines I've flown with actually do enforce it. At least for the first and business, and small children. If your group isn't called they'll ask you to stand aside so that group can go. Some people really push it and the crew would rather not get in a confrontation and let them pass.
