...unlike Amazon and Barnes&Noble who refuse to sell ebooks to non-Americans O'Reilly doesn't have this restriction
I don't know about the Barnes&Noble selling model, but the Amazon e-book model may well be illegal in Europe from what I understand (it's to do with what is technicaly an illegal cross subsiding of the business).
Also... some books in the USA due to other US legislation can not be sold in Europe which doesn't apply to the O'Reilly books as none of them are anywhere near old enough.
Oh and then there is still the hang over from the "export on munitions" legislation that apparently does not apply to information in printed books but does to electronic books. Put simply a book with a printed software section is ok but the same software in electronic form is not. This has found it's way into ordinary copyright issues as has been seen in one or two "cease and desist" claims where publishers are trying to ring fence basic knowledge and mathmatics as being proprietary property.
A recentish example was over the "time" database where a publisher of astrology books claimed that information "proprietory to them" had been put into the database. The claim was highly dubious at best even in the US (and not enforcable else where), but when an individual is faced off by a corporation with on staff legal personal highly knowledgable in the area who get paid regardless, and the individual having to pay very high rates for their own legal representatives, capitulation is almost certainly guaranteed. Which is what these shyster companies relie upon.
Even where the individual knows theyy are legaly right, they probably will decide not to fight the company because they will invariably just fire off multiple injunctions with delaying tactics to keep the individual making the information available...
Realisticaly at the end of the day it has nothing to do with what is and is not right but the Mickey Mouse Corp and their fiends buying off US legislators to protect their closed market.
The likes of Amazon have to make a choice support little guys rights and lose the rights to market big earnings media or... I guess the old "money talks..." adage applies.
There are only two ways to change this effect significantly the corperate bottom line, or put the corperate officers (executive or not) in fear one way or another. Their greatest fear of course being ridicule and humiliation in the shareholders eyes, shortly followed by loss of status, oddly imprisonment following trial does not even make it onto their radar which is a major tell...