At the very least, evidence demonstrating a persistent, long-term trend would seem to be evidence in favor of the trend applying to the current day. Especially when the main thing driving people's perception that life is _not_ getting better seems to be media reporting that fails to focus on the big picture. In other words, the world could be improving while (of course) human lives are partly bad. Focusing on the bad --which can always be found -- and not on the overall general trend skews our perception about whether and how things are changing.

Of course, there could be countervailing reasons (and evidence) that the general trend does not hold currently, like the suggestion that (a) distribution of benefits has become more uneven and (b) this uneven distribution may make things worse overall than they were before the benefits existed in the first place.

There are lots of ways people could try to provide evidence that the general trend somehow no longer applies. But I think the linked article points out: this sort of evidence is not what media is giving. News media points out that something is bad, sure, but it fails to place it in broader context. The broader context is one of general slow improvement over long periods of time, which is something that we don't get from the news; news media likes to focus on today's bad things, long general trends are not "newsworthy".

Also, as the article suggests, even today's positive evidence for the general trend is not newsworthy, in part because it is so pervasive and boring (e.g., every day 130,000 fewer people are living in extreme poverty). Something that happens regularly every day is not "news". (Or maybe the 130k fewer people thing is not news mostly because it's a good thing. The rate of murders and/or car accidents can be fairly stable, but people seem to have an appetite for hearing about each of these bad things as it happens, so that's what news reports.)