The tank mods are added by retailers and print shops. You're right about how the system works -- the lines run from the big tanks and are inserted through a hole drilled into the carts small reservoir.

One issue with that is that most cartridges have a software page count that is used to tell you that the ink is running low / empty after a certain number of prints. So, along with the tank install, most shops will put in an aftermarket chip or PCB that resets or bypasses that counter.

For the other question, I think that Thailand still relies on printed documents more than in the US, but it is going down. I undoubtedly have a somewhat skewed opinion on things since I am a teacher, though. I teach 18 different classes of roughly 40 kids once a week, with a worksheet or some other printout being used nearly every week -- so I probably burn 700+ pages each week through my school's copy machines. Then I teach smaller private classes at home, with maybe 100 or so pages a week on my own printer(s). I have one inkjet with those tanks installed, 2 mono lasers, and 1 color laser... So yeah, I probably am a much heavier user of printed stuff than your average person.

Cheap inkjets are horrible, but try printing photos with a laser printer...
And a lot of color laser printers print tracking dots on every page you print. Yay!

Cheap b/w laser printers are ok, but if you need color don't buy the cheapest inkjet printer/scanner/fax/toaster/radio all-in-one POS you find, spend a little extra cash on a proper inkjet printer (without a ton of built-in crap).

Hmmm, Office Max will take my pennies??? I smell a follow up vid....

"This wheelbarrow of pennies I've been carrying sure is burning a hole in my pocket and I have been wanting that color laser printer for some time now... off to Office Max with my pennies and my camera!"

As color laser printers are now cheaper than their respective replacement cartridges, when you're out of toner, you throw the old printer away and buy a new one.