A bus is, however, a Faraday cage.
A cell phone has a limited antenna and little power to amplify a signal. A lot of filtering needed. What is left is often not so great. A cell phone is also a transiever. Transmitting out is more of an issue.
In other words, metal and enough thickness of cement absorbs signals. Each material has a specific set of frequencies it will be more efficient in absorbing, but will affect things across the board.
If you drive through tunnels, you will also notice bad FM reception, so this is certainly not limited to AM.
With the lighting, you are picking up some of the signal from the power (florescents are really bad) and your radio is amplifying this. Again, no blocking but your radio cannot seperate the good signal from electronic noise. This is part of the basis for electronic warfare. A jamming signal is simply a stronger transmission (locally) through a set of frequencies.
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