The shebang line is not interpreted by the shell. It's used by the operating system kernel to figure out how to execute a file that has the executable bit on and is not a "real" binary executable. I believe it goes more or less like this:

You (maybe via a shell)

Hey, OS! Please execute ./test.pl

OS

Hm, this doesn't look like a binary, but it starts with #!. Let's see... Oh, I should tell /usr/bin/perl to handle it. (executes /usr/bin/perl)

OS

Hey, perl, there you are! Run with ./test.pl as your first argument (some systems might include all arguments from the shebang line at this stage).

perl

(Opens ./test.pl). Hey, this looks like a Perl program with a shebang line! Let's see if there are any options in the shebang line that I didn't get already when I was exec'ed... (figures out the options; compiles and runs the program).

Since tilde, alias, and other expansions are done by the shell, they don't work on the shebang line.