Here's a variation on one of your examples that show the difference between INIT and BEGIN:

use 5.010;
use strict;
use warnings;
persist();
INIT {
    my $store = init_store();
    sub persist {
        say $store++;
    }
}
persist();
persist();

sub init_store { 0 }
__END__
0
1
2
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But if you change the INIT into a BEGIN, you get a run-time error:

Undefined subroutine &main::init_store called at /tmp/xxx line 10.
BEGIN failed--compilation aborted at /tmp/xxx line 14.
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