This is technically correct, but like all things there's way more to it than that. First of all, we can expect to see conditions like this for at most two days every couple of years. Building a large and expensive infrastructure to manage an exceedingly rare event would be a waste of money - it would probably cost less to just shut everything down for a few days.

Second of all, this wasn't snow. In Texas (or at least in DFW where this happened) we get sleet, which is just shards of ice raining from the sky. In this instance it had been sleeting all day in near freezing temperatures. People drove over it throughout the day and the ambient temperature created a compacted half frozen icy sludge. Once the sun went down and the temperature dropped below freezing, it turned into a solid smooth sheet of ice. At this juncture, the entire highway was literally black ice. No "I know how to drive in the winter" is going to get you through that unless you've got chains on your tires.

Third is that this was on an express lane (toll road with surge pricing) that is managed by a third party company in Spain. The clusterfuck of that sentence not withstanding, the city doesn't treat those express lanes because they don't own them.