You are making two common mistakes here -- 1) by assuming that the cost of labor is the only factor in the price of a product or service, and 2) by neglecting the impact of inflation on the price of a product or service.
In the case of home prices, there are a number of major factors that have driven them up dramatically -- the higher cost of land, the additional permits to build, and the higher demand due to population growth. If you were to take that same $450,000 new home in a metropolitan area in California and construct it instead in the middle of Nebraska, you'd be amazed how cheap it would be (especially if it were built with Mexican labor).
As far as lettuce is concerned, there is an inherent price instability for almost any agricultural commodity, due to variations from one year to the next in crop yield, weather, etc. Beyond that, the prices of many agricultural commodities (milk being one of them) are set at artificially high levels due to government interference in the market.
But regardless of these causes of seemingly high prices, I would wager that when you take the impact of inflation into account, the vast majority of products and services are cheaper today than they were in the 1970s.