Apparently my brother doesn't know that these aren't raw bytes made up from the pits and lands, but rather bytes using an error-resistant algorithm.
Also, *I* (Not he) was referring to a CD jewl case design that doesn't need to be opened (But CAN be), similar to a caddy. Because of this, it would cost absolutely nothing more to manufacturer. "Free" CDs would still be rampant due to the availability of "empty" caddys. The cartridge idea means and optional piece of silicon with a connector edge has a place on the caddy and the drives can read it. Carts are only expensive when you are trying to store tons of data on them. In this case, the CD is for storage. The cart will only contain a KB or so of data. An encryption key, or even just a bit of data that the software will refuse to run without. Also, it could use EEPROM or SRAM like a Nintendo cartridge to save password/progress/save data for games and such 🙂 People pirate carts often now. It's almost impossible to order an import GBA game off of eBay without getting a pirated one (The cheapest are around $10!). So it's not that expensive anymore!