I mean, do you ever pay attention to the first time a title character is shown with a cellphone? A home computer? In the much older comics even a tv. Going back to the 1930s, I'd even say washing machines and refrigerators, but that's not the kind of thing we saw in those days, I don't think. I was thinking about it because I'd read some silver age western comics, and, of course, they were often standard westerns, despite (at least at times) being set in the 1880s, the towns didn't seem to have running water or electricity like some western towns did then (of course, they weren't really consistent on size, either, and that matters). And then there was PowWow, which was set in the then-present, but treated so often as though it were in the past that it got moved there. I kind wonder if it was moved because fans tended to assume it was in the past or because even the rural areas were modernizing too much to pull it off by then.
Nonetheless, actual stories written in the time they were at are more useful because, unlike westerns, they aren't intentionally presenting an era that never really existed in the way presented, but the world they lived in. Certainly in some of the old stories, even when it wasn't the point, we'd see the kind of urban poverty that doesn't exist anymore (not that urban poverty doesn't exist, but it doesn't look like it did back then). I've even noticed the hairstyle and clothing changes. But that's not as specific and easily markable/measurable and consumer devices. Especially for the non-rich heroes. But the mundane everyday devices that don't effect heroing that didn't exist when the comic started, when did we first see characters use them? Just sitting in the background or whatnot. Or even ones that could effect heroing, like cellphones. Though we see comms used, of course, I can't really remember when that started. I remember Dick having a pager in '90s Nightwing.