One of main complaints of the article - that airline staff doesn't get passed enough information about a passenger's disability, so, for example, deaf people get met at the gate with a wheelchair, seems to be a direct result of using inappropriate, or non-standard, SSR codes. If a deaf/hard-of-hearing person is travelling, the appropriate code, (DEAF), should be used, not HI or MAAS, (if the systems allow for multiple codes, "DEAF MAAS" would be appropriate).
According to the article these SSR codes are industry standards and are entrenched in airline systems worldwide. If they were used properly, and if staff were properly trained to understand and act on them, this problem would largely be solved. This is a training & execution problem, not a technology problem.
A second complaint, that information is not passed to disabled customers quickly, (for example, hard-of-hearing passengers can't hear announcements at the airport or on the plane), is also mostly solvable by using the tech that is installed in airports today. For example: "Visual paging — when an audio page is posted in text form on screens — is becoming very easy, but it’s not yet ubiquitous." Why is it not ubiquitous? Haven't most airports, at least in wealthy countries, got some sort of a screen up at each gate that has the Flight #, departure time, weather at the destination, and all that? If announcements aren't going up there too that seems to be laziness or lack of training on behalf of the gate staff, or laziness or lack of concern in whoever makes decisions about how the software that runs those screens works.
For in-flight announcements it's harder, especially now that seat-back displays are being removed from aircraft in favour of handheld devices. It probably comes down to a flight attendant making sure that a disabled person gets told what's going on, (because he or she saw the appropriate SSR code on the passenger manifest).
The final complaint, in-flight entertainment, is ridiculous. Why isn't everything that's available on TV, (closed-captioning, described video, and whatever else I'm not aware of), available on in-flight entertainment? The tech exists, it looks like it just hasn't been installed, or has been installed but isn't activated, on aircraft. This should not even be a problem and I don't understand why it is.
Edit: To clarify, I'm not disabled, and haven't experienced these problems myself. This comment is based purely on the problems as described in the linked article.