I confess to still not understanding why roof installs cost so much more. My ground mount array(s) required concrete foundations that were 5' deep and 17" in d

I confess to still not understanding why roof installs cost so much more. My ground mount array(s) required concrete foundations that were 5' deep and 17" in diameter, and the frame cost $2k in iron piping. There's nothing remotely comparable in a roof install. I guess people just charge more because "we're on your roof, which is tricky".