It's strange that oxygen cannot be transported at night. In Europe all the critical and big volume transports goes often at night (wind turbines parts, ship components etc.)
Lots of places around the world have really terrible roads and nonexistent or nearly entirely unenforced road laws. Places like that you might want to be careful to not drive an enormous tank of flaming death around when you’re not so sure you can see each of 500 pot holes, or an oncoming driver.
Basic infrastructure things are easily taken for granted.
Otherwise you would know that this _may easily_ result in an accident and no-one wants to have a truck full of O2 to blow up in the night in the middle of nowhere. At least during the day „you see where you go“.