I'm afraid that your code as supplied doesn't compile for me. Using Class::Struct 0.65 with perl v5.20.3 I see:

syntax error at 11123269.pl line 11, near "struct Carrier_Info"
Execution of 11123269.pl aborted due to compilation errors.
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This seems reasonable because the documentation suggests that the arguments to struct should be within brackets. Is this really the code you are running?

Update: here's an SSCCE showing what I think you expect to be output.

#!/usr/bin/env perl 
use strict;
use warnings;

package Carrier_Info;

use Class::Struct;

struct (Carrier_Info => {
          name => '$',
          abbrev => '$',
});

my $aa = "TH";
my @carriers;

push @carriers, Carrier_Info->new(name => "Paul Lalli", abbrev =>"PL")
+;
push @carriers, Carrier_Info->new(name => "Travis Hervey", abbrev=> $a
+a);

my $xyz = pop(@carriers);
my $ppp = $xyz->name;

print "which name is $ppp\n";
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I won't claim this is the neatest as I never use Class::Struct directly but hopefully it will serve as an illustration.