Our first 2 TT's had no slides for the same reasons. No slides, no leaks, no slides getting stuck in extracted position. But after several years, the 2nd TT also ran out of room.
So when searching for a new camper, we needed clarification on 2 items.
1. Is the camper 100% functional AND EVERYTHING accessible with all slides "in".
2. In the event of 100% power failure, how do you retract them manually.
I haggled with the dealer over these 2 items. We opened slides, we closed slides, he explained in detail how to retract manually. We spent some considerable time in the camper with the slides "in". We bought the camper in August 2013! (see my signature and profile).
Now that we are "driveway camping" since most campgrounds are now closed in Indiana, we're experimenting "driveway camping" on week-ends now with the slides "in". Except for watching the big television in the living room, the camper functions quite well. We did install a second television in the bedroom so we don't have to watch it in the living room.
Reason we want the experience with slides "in" is so if we ever do end up in a spot, or traveling and stop at a rest area or even a Wall Mart parking lot over night, we know how to function in the camper with all slides retracted. So far, we've done 2 weekends with slides "in" and it functions remarkably well.
There again, after all this rambling, to answer your original question, yes the slides can be retracted in a manual way, without using the battery operated motor.