Great whataboutism. I assume you mean roadkill? That makes one relatively small chance of directly affecting (not necessarily killing) one animal in wider area. One firework has pretty much guaranteed chance of affecting all animals in wide area.
The utility of the firework is also zero compared to a vehicle. In a vehicle you have a chancenof affecting the outcome of potential collision. You can drive more safely when the chance of encountering animals is higher.
And about the nearly 0 chance of death - I don’tbhave statistics but have some examples of pets dying due to shock. There was this village where fireworks got banned because every year a couple of horses died on New Years. A couple of years back there was really eye opening picture (I think from Rome) where a whole square was littered by dead pigeons morning after New Years.
And less not forgey the stress and suffering caused to countless others that don’t die. Discounting them is like saying tortuting is ok because people usually survive it.
And if you don’t care about animals, think about the PTSD of war veterans or other people living through war. Plus the polution and smoke is not good for the health, not mentioning the lost fingers that strain health care for that day.
Is a few pretty explosions really worth others suffering (especially when there are now ways to have light shows without or with considerably less negative effects)?