Based on the news stories, this instance looks like a fairly classic case of impatience. There are 4 tracks at the location: 2 UP and 2 light rail. The stories suggest there had been 2 UP trains passing and occupying the crossing for some time. They cleared, but the gates didn't clear because the light rail train was coming. The person in the SUV pulled out of line and went around on the wrong side of the road. Given the results I don't think we'll ever know for sure why.

It's not a very big road, but a lot of smaller streets get used for cut-through traffic in Sacramento. Chez Google: [maps.google.com]

I agree that grade separation is the gold standard, and should be done wherever feasible. However, they're expensive -- many million$ for even a basic one because of the bridge involved, and more if it's the railroad on the bridge instead of the road -- so they tend to happen mainly at major roads where there's enough train traffic to cause serious road traffic backups. The effect on road traffic is the reason why RT has a few rail-highway grade separations, though safety is a useful byproduct.