The iPad doesn't support Flash and plenty of less-than-technophiles use it as an everything computer.
What does the "don't have flash" stub look like? Does the ipad recognize embedded flash and show a friendly explanation or is that left to the site?
It's left to the site to detect the missing plugin.
If the site doesn't have a helpful explanation, there is a blue lego piece with a question mark on it. I cant remember if there is anything else.
Maybe not right now, but maybe soon HTML5 will be more widely adopted to make flash much less important for everyday browsing.
I disable plugins in Chrome and only run Flash as-needed, mostly for video and occasionally for something like the Facebook photo uploader. Life without Flash is certainly possible today.