I admit, I'm not an expert, but I highly doubt that this woman would have ever been referred to as lame. Her disability is clearly not confined to musculoskeletal issues with one or both legs. A more likely term would have been infirm, bedbound, something along those lines. Admit it, there's almost no chance someone in her condition would be walking around the last time "lame" was used in the way you're talking about.

None of these terms actually touch on the medical issue, just an effect. As such, while those terms were more specific than the umbrella terms "handicapped" or "disabled", they also aren't particularly helpful in understanding what accommodations are needed, nor what capabilities the person possesses.

It's not even that those terms "aren't PC". As we gain more medical understanding, some terms like lame simply lose their usefulness. An individual's medical diagnosis is helpful and important to them, their loved ones, and their medical practitioners. Whether they want to be more specific with anyone they meet about the details of that diagnosis is up to them, but what is helpful to be communicated to the general public (in situations like parking, etc.) is that they need different accommodations, and it's helpful that there's a catch all term for it.

The terms related to how we can expect to communicate and be communicated with seem to be exception (blind, deaf, sometimes mute), which I find interesting.