I'd say you're almost right about nobody asking for infinite value, but I'd say it's more like nobody who has pulled this up to the conscious level is asking for infinite value. People who have not examined the belief are quite prone to speaking as if life's value is infinite... but their own actions inevitably belie that claim. Once examined, it becomes rationally obvious that life is not infinitely valuable (including your own), but, well, if humans automatically accepted and believed all rational things they examine without emotional consequence the world would be a very different place.
http://www.nytimes.com/2011/02/17/business/economy/17regulat...
For evaluating safety regulations relative to the cost of inplementation, NHTSA values the risk of loss of human life in relation to the market value of risk reducing products, and the safety they provide.
They extrapolate from the take rate of airbags and their cost and effectivity, to how much value the average American places on their own life. IIRC on the order of $5 million.
FYI, juries do not look kindly on companies that implement this in liability suits. The data is that if a corporation writes down a $-figure for a (statistical) human life, it anchors punitive fines at a higher level.
However comforting that logic may be, it is unusable in the real world. If you value lives infinitely, then you will never ever do anything that risks your or somebody else's life in order to gain on any other need. You routinely engage in things that are not the safest possible option in order to fulfill other needs, ranging from food or water acquisition through mere entertainment. Therefore you place a finite value on your life. Don't feel bad, so does everybody else. It is possible to determine the value placed on life, I believe there are studies that show the value is more stable than you might think, and balance things appropriately.
It may be uncomfortable thinking, but, again, unless you literally never take even the smallest risk in the pursuit of other goals, you are already thinking this way. You just haven't lifted it up to the conscious level yet.