Don't set fire to your brain then, problem solved.
Because it's often clear, folks often think that plastic is inert like glass. It is far from it.
Obviously water bottles should be made from plastics that don't leach anything harmful into the water when left in a hot car. To the extent they do, it should be easy to come up with specific arguments to prohibit specific substances. Just blaming "plastics" in general is a category error, since not all plastics are proven to be harmful in this regard.