Thanks for the feedback! I figured relining wouldn't work for us. Our options are:
1) leave leaky pipes alone and lay new drain pipes outside of slab, tapping into city's lateral near the street, or
2) dig under slab 20+ feet to replace failing pipes, or
3) dig under slab 70+ feet to replace all pipes.
My folks are retired and on fixed income, I'm self employed and their caregiver (not much disposable income), the house is paid for, and we have no plans to sell. Since the camera showed the main lines are good, we're eliminating option #3 for now. Our house sits on a bunch of caliche, so we know that digging under the slab (option #2 or 3) will be more expensive than the initial estimate, 'cause they are gonna run into rock (as happened with our neighbors).
That leaves us with option #1 -- they will run a new drain from the kitchen sink through the wall and attach it to a new pipe in the back yard, below ground and far enough from the house to avoid utility lines. Turn the corner and pick up a new connection from the washer (which is in the garage, just off the kitchen), then continue on toward the street. The city will tap the lateral. Total length of new line is around 65 feet.