Rubbish: all trees outside of deserts concentrate roots near the surface. While on the one hand coast redwood is basically the biggest tree in the world (when proportions reported for specimens no longer standing are considered) red maple is no small bush either - if you feel the planting locations cannot support full-sized trees growing over 60' high and so on then the maples are not going to work out.

And in California I would probably not give the space to a cold climate tree like red maple, that does not require the California climate - instead planting something that I couldn't grow in most other parts of the country.

If the red maples were their idea then that's two ways they are not giving you the best service (the first being the hogwash about them rooting down, away from the wall, in a manner completely different from the redwoods). Depending on what specific part of California you are in the maples won't necessarily be completely happy on your place as well.

Thanks for the follow-up bboy. I'm in zone 9. Yeah the one that is about 20 inches from the wall makes me really nervous just with an expanding trunk over the years.

I'll keep looking for alternatives and dig them up before the spring.

I just saw this pot and laughed.
Roots down? Huh? They're not tap root trees.
I have a couple of October Glorys and Autumn Blazes. Huge root systems.

Have you ever had a garden & tried to plant something around a maple? First, not only do you have to dig through a spiderweb of roots, the replacement roots will suck the life out of the soil. Hosta and Hellebores are your best bet.

I just had a downspout water pipe run beside my house. I have a tornado-downed maple that was probably 30 years old. They guys are using a chain saw to cut through huge roots more than 15' away.

I'd find a happier place for these trees, even if I had to sell them online. The advice above is wise.

20" OMG. what kind of a landscaper are these fellows?

What did you end up doing?