A hyphen placed at the beginning of a character class or tr/// search/replace list is also interpreted literally:

Win8 Strawberry 5.8.9.5 (32)  Sun 04/17/2022 18:43:19
C:\@Work\Perl\monks
>perl

use strict;
use warnings;

my $s = '123-abc-456';
$s =~ tr/-a-z//cd;
print "'$s' \n";

$s = '123-xyz-456';
$s =~ s/[^-a-z]//g;
print "'$s' \n";

^Z
'-abc-'
'-xyz-'
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But one can argue that one is as likely to place new stuff at the start as at the end, so escaping remains wise. :)