All freeways must absolutely have no at-grade railroad crossings. If that picture shows it has one, then it should be an expressway.
That picture is pretty rare.
It seems like the examples being given are State Highway and US Routes. I’d say that more isn’t adherence to Interstate standards than said segment not being a freeway. I’d be curious to see anyone has an example from the Interstate System.
In California, the definition of a "freeway" requires grade separation. There are many California freeways that have "END FREEWAY" signs for an at grade crossing (either for cars, railroads, or boats) that have "BEGIN FREEWAY / EMERGENCY PARKING ONLY" signs a few hundred meters later. By our definition, freeways can have lots of things that are Interstate substandard or completely nonstandard (narrow lanes, narrow shoulders, narrow or artificial media, short merges, low vertical clearances, no guard rails {just a fence}, "hole in the fence" exits, bad sight lines, low design speeds, sharp curves, and steep grades {and you can probably find at least 10 examples of each in California -- we have lots of freeways}), but the minute that there is an at grade crossing, it's not a freeway.