Upvoted for the impressive feat of cramming Apple fanboyism and subtly flawed linguistic pedantry into three dozen words of double-barrelled flamebait. Downvoted for posting double-barrelled flamebait comprising Apple fanboyism and subtly flawed linguistic pedantry.

machine-unreadable HTML tables

The whole point of HTML is to be machine-readable.

That HTML's meant to be machine-readable doesn't mean it is. (Both webpages and browsers can fail to meet HTML standards.) But that is itself a counter-nitpick. The bigger problem with your nitpick is that you're reading "machine-readable" in a blinkered way. As Wikipedia says, "machine-readable" data can refer to "human-readable data that is marked up so that it can also be read by machines (examples; microformats, RDFa) or data file formats intended principally for machines (RDF, XML, JSON)". You seem to have only the first meaning in mind while I was thinking of the second. I wanted the data in a format that a computer could immediately interpret and turn into a scatterplot, such as a text file of two tab-delimited columns of numbers. Now, you do make the point that it's fairly straightforward to get the data as two columns of numbers...

I find that if I copy a table from Apple's web browser and paste it into Apple's spreadsheet, it works fine. Maybe you need better machines.

...but telling me this is unhelpful. For one thing, I already have two spreadsheet programs on my computer that can do the same thing, Gnumeric and OpenOffice.org Calc. For another, why should I have to change my usual workflow (paste data into vim, clean it, save as plain text, load into R, make graphs) when the data could've been made available in a simple format in the first place? Lastly, once you've got the numbers into your spreadsheet, what happens when you try plotting them? Do you still "find that [...] it works fine"? I suspect not, because the age numbers include values like "< 0.001", "0.004 ± 0.001", "0.0054± 0.0015", "~ 0.0066", "> 0.05", ">5, <36", and "3-95". Being able to circumvent the clunkiness of presenting data in HTML tables doesn't eliminate the problem of the ad hoc human-readable-but-machine-unreadable notations.