Oh, what I meant is that the indash changer is a complicated unit, internally. There is a lot going on in the CD transport mechanism, there is a lot of moving parts and electronics to it. I am a bit of a purist and having too many moving parts is one of the reasons I don't especially care for indash changers, power windows, electric door locks and power moonroofs, and other things like that. They are just one more thing that can break, IMHO. A car or truck is a hostile and harsh enough environment as it is without adding a bunch of sensitive electronics to it. That being said, I guess modern electronics have come a long way since 1990's technology. My girlfriend has a 2003 Accord with the indash 6 disc changer and it is still working fine. But she had the driver's window regulator replaced about 2 years ago - before I met her, and I recently replaced the master power lock and window switch and the driver's door lock actuator for her.
If the indash 6 disc unit breaks, I imagine it would cost a lot more to fix it than to fix a single disc unit. I remember way back in the 1990's when Alpine came out with the indash 3 disc changer that had this funky Z-mechanism to load the CD's. It was kind of an installer's nightmare and they didn't sell very well either. The separate 6 disc changer that went in the trunk or behind the seat did very well though. Back when I was in the car audio business that was the big thing, to interface a changer to the factory radio. A lot of suppliers made interfaces for the 6 disc Alpine changer to the OEM radio. When I retired from car audio the big thing was to interface the steering wheel controls with an aftermarket radio. The suppliers were going nuts with that right about the time I quit the car audio business.
I am too old to be much of an installer now but I still keep up with the car audio world to a degree, and have continued to do my own systems and alarms, plus I have done it for a friend or two. It takes me a lot longer now than it did then and I am sore the next day, but I still get a kick out of it.