Interesting point, stevedekorte. Currently propane is distributed by a kind of hybrid of both methods: you can have your tank refilled from a pipe at (many) gas stations, or you can swap your empty tank for a full one at some lumberyards and large home and garden type stores (Home Depot, Walmart, K-Mart, etc.).

Hydrogen actually has a safety advantage over both propane and gasoline: at typically encountered temperatures, it's lighter than air. The big hazard with gasoline (vapors) and propane is that any leakage tends to flow downhill and accumulate, rather than rising and dissipating into the atmosphere.