That's an interesting observation...
Sure it will cost them a little, but if you can convince them that it is like an insurance policy...
They really have nothing to lose. But on their own, how much do they stand to lose if they choose a contractor that cuts corners.
Would a homeowner be able to tell the difference between a 50 yard pile of topsoil and 100 yard pile? Could they determine how much base they need for their new paver patio based on the sub-soil? Would they even realize the importance of drainage behind a retaining wall?
On the other hand (we'll call this hand LawnLad's), we now have the Internet. And everyone, including homeowners are quickly becoming experts at everything. Why would they pay somebody when they can just look up all the information they need to become an "expert" in their own mind.
I agree with LawnLad, it may be a hard-sell. But if you can establish trust and at the same time, get them to realize that there is far to much knowledge for them to master in a short period of time, there very well could be a market, even if you have to create the market at the time you are selling yourself.
But you certainly would have to figure out a way to make sure there was no conflict of interest on your behalf (kick backs, buddies doing the work, etc) - as this might spoil the trust with the client.
This would surely have to be brought out in the open up front. There would be a level of trust that would have to be acheived, without a doubt. It would be best if you didn't provide any names of companies. Only give advice after they have received the bids. And then let them know if you personally know anyone working for either company, regardless of which bid you reccomend.