Well, cows can't decide 'this transport is going to be uncomfortable or possibly dangerous, but I really want to go to the other place, so I'll deal with it'. Would you rather have uncomfortable, possibly dangerous transport or no transport? Yes, you'd rather have comfortable, unlikely to be dangerous transport, but that doesn't seem to be something the transportation network is able to offer.
The employment industry in our prevailing economic structure demands punctuality, often through crowded, uncomfortable and frankly, degrading means of transportation. This perceived "choice" is not a luxury but an enforced necessity, much like the bovine passenger being shipped off to slaughter, with the only distinction being, we humans "chose" this.
One could argue that the transportation network isn't able to offer comfortable and safe transit, yet it is more a matter of priorities than abilities. The ability to provide such transport exists, but the political and economic will, sadly is not in abundance.
Is it not curious that a society which can show empathy for the transportation of its livestock struggles to extend the same basic courtesy to its own kind? After all, are we not more than just cattle to the abattoir of capitalism?
The steel box for humans is allowed to be hotter and more crowded than the steel box for cows.
Slaughter doesn't have to be involved. The same rules apply if you're transporting a cow from one field to another field.