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If you want to run the byState executable that is found in a particular directory, as opposed to the one (if any) found in any of the $PATH directories, you need to invoke it by its path. As that has to contain at least one /, for the one that is in the current working directory, you typically use ./byState which, like byState is a relative path to that file, but is one that contains a /. You could also use /full/path/to/byState or ././byState or ../here/byState which would also work.

If you want to run the byState executable that is found in a particular directory, as opposed to the first one (if any) found in any of the $PATH directories, you need to invoke it by its path. As that has to contain at least one /, for the one that is in the current working directory, you typically use ./byState which, like byState is a relative path to that file, but is one that contains a /. You could also use /full/path/to/byState or ././byState or ../here/byState which would also work.

Or factorising the print "\t" $1 and making it more legible / straightforward:

#! /bin/sh -
sort -t, -k4,4 -- "$@" |
  LC_ALL=C awk -F, '
    $4 != LastState {print LastState = $4}
    {print "\t" $1}'

^{¹ For those that are not otherwise a shell builtin command or function or alias (when literal) of one of the keywords in the shell syntax such as while, for... (also when literal).}

^{² Decades ago, it was not uncommon to include . or the empty string, both of which mean the current working directory in $PATH where you would run into this kind of problem, but nobody would be foolish enough to do it these days.}

^{¹ For those that are not otherwise a shell builtin command or function or alias (when literal and unquoted) of one of the keywords in the shell syntax such as while, for... (also when literal and unquoted).}

^{² Decades ago, it was not uncommon to include . or the empty string, both of which mean the current working directory in $PATH, even at the front (!) where you would run into this kind of problem, but nobody would be foolish enough to do it these days.}