The most surprising aspect to me about this is that it passed unanimously!
This law is a Big Government law. Where are all the Small Government advocates?
If you think about it, the main implication of Time Zones is on commerce. Before mechanical clocks (and instant communication) each locale could have it's own clock (determined by a sundial). Major tampering with time zones seems to occur with centralized power. The most obvious examples of those are Russia and Turkey. Private businesses can decide at what time to start and end their days or shifts, regardless of the mandated time zone or ST vs DST. The place where it matters is government (whether government offices, or local ordinances which are time dependent such as parking, construction/noise, etc.)
Wouldn't it make more sense to split each of the current US time zones into two (30 minutes apart) and give each locale the option to choose their time zone?