Most people use the printers they have at home about once (or less!) a week and these are only used for fast drafts in black and white. So there's no real need for a full color cartridge and such a huge volume. Besides home use the portable all-in-one may be quite handy in meetings that sometimes take place outside the office (trade fairs, restaurants...).
The ideia behind myBrother is to reduce the volume of this so little used equipment by using thermal printing. This method uses thermal paper, a special fine paper that is coated with a chemical that changes color when exposed to heat. Nowadays to replace the toners of traditional all-in-one's you end up spending almost the same of a new printer. With thermal printing you don't need to replace anything and each sheet costs less than 0.10€.
Inside the box are the rolls that pull the paper by its non-printable margins, a CCD-array for scanning, and rolls for thermal printing.