I am just curious, because I understand but don't 100% understand why.
I know that some things can block radio signals but does anyone know
why this is.

If I take a local transit bus in my area, whether it is a big or a
small bus, on a walkman or scanner, their is usually little to no AM
at all. Some FM stations go haywire. Shortwave, on the bus dead. When
I go into my college, shortwave dead.

When I am in my house, I can easily get AM stations and shortwave, why
do some buildings just kill the signals?

Also, does anyone know, did McDonalds go encrypted or something with
their drive-thru? I have a Uniden BR330T scanner that includes drive-
thru ranges, and in my area of my college, there is 3 restraunts with
drive-thrus. One KFC, One McDonalds, and one Wendys, all right next to
each other. Now I have always been able to get KFC and Wendys with
usually only a search. No matter what I do, I can never seem to get
McDonalds on my scanner even trying known frequencies. I know for a
fact they use wireless headphones because when I went in to give an
order, I saw a pair behind the counter. Why is McDonalds the only
place I can never get on my scanner?