NB: This is a viewpoint by Mark Smith, founder of The Man in Seat 61, the rail travel bible.
I spend my life railing at French rail operator SNCF's Machiavellian approach to international distribution.
How much better it would be if Deutsche Bahn (DB), Trenitalia, Renfe, and SNCF made seats bookable through one system with one global website that everyone could use in several languages.
SNCF still thinks there are different 'webs' in different continents, not a single World Wide Web. For a single train, SNCF apparently requires four different organisations to sell seats:

1) SNCF themselves (voyages-sncf.com and tgv-europe.com),
2) Rail Europe 4A (Australia, Africa, Asia, South America),
3) Rail Europe Inc (North America) and
4) Rail Europe Ltd (UK).
Each site (or group of sites) has different fees and different functionality. For instance,Rail Europe Inc suppresses the cheapest fares for the US market.
That means Americans can avoid fees and marked-up prices by instead booking direct with SNCF at tgv-europe.com and pretending to be a resident of Europe as ticket delivery country.
So I am constantly telling travellers to book at tgv-europe.com, selecting 'Afghanistan' as the ticket delivery country (it begins with A so is at the top, and who cares where you live if the system can give you a self-print or collect-at-station ticket?)
I'm confident that on the strength of the sales figures, any day now we'll see French Railways will be open a Boutique SNCF in downtown Kabul... ;0)
Recently there's been a spate of 'My credit card has been rejected by tgv-europe.com' emails and Tripadvisor posts, I don't know if this is another Machivellian conspiracy to stop people buying at the correct European price if they are from the US, or just a cock-up.
But this is why I'm increasingly suggesting Capitaine Train or Loco2 to travelers.
Capitaine Train sells SNCF, Deutsche Bahn, Eurostar, and Thalys tickets. (See previous Tnooz story on Capitaine Train.)
Loco2 accepts a feed from Rail Europe UK, which has European prices albeit converted to pounds, but unlike Rail Europe Ltd themselves they accept all credit cards, so can be used by anyone if you get a self-print or collect-at-station delivery option for that specific train and ticket.
Loco2 connects to DB and Eurostar as well, and can sell self-print tickets for DB & Eurostar at DB/Eurostar prices and no fees.
Indeed, where they show two identical journeys right next to each other, one with a DB price the other with the Raileurope French Railways price, the difference can be an eye-opener! (See previous Tnooz story on Loco2.)
A pan-European booking problem
So far, I've only talked about the hassles of booking French trains online from overseas.
There's a wider issue of why you need so many different sites to book one journey, i.e., you need to go to trenitalia.com for Italian trains, bahn.de for German trains, tgv-europe.com for French trains.
Say you want to book a journey from Zurich to Rome. You'll need to be split it into a ticket purchase from Swiss rail company sbb.ch for the Zurich to Milan leg (to get the fares from €22), then trenitalia.com to get fares (from the cheapest €9 for Milan-Rome).
If you instead book Zurich to Rome at sbb.ch, the Swiss cannot access the full Trenitalia fare range and so will charge a full price ful-flex fare for the Milan-Rome bit.
Frustrating!
The big picture
There's a wider issue of why you need so many different sites to book one journey.
If Google starts suggesting train times and directing people to trains, that's a good thing. But I only see Google someday doing this for easy one-train one-operator journeys where it happens to have an agreement with that operator.
The problem is one of fragmentation, and what's needed is a system which integrates, rather than just acts as a portal, like Google.
So that you can enter, say, a trip from Zermatt to Florence, and have the system book the Zermatt-Brig ticket with SBB, Brig-Milan at the cheap rate with SBB, and Milan-Florence at the cheap rate with Trenitalia.
I can't see Google having the expertise and application interest to do this.
Mobile app development years behind
In February 2013, Eurail Group launched the Rail Planner App. But it has its flaws.
I recommend instead Deutsche Bahn's DB Navigator app, which has train times all over Europe, probably using the same base MERITS data as the Eurail app.
Like most commentators, I am increasingly cynical about railpasses, such as from Eurail or Interrail, which certainly don't save money over today's 'budget train fares' and often don't save money over fully-flex fares.
NB: This is a viewpoint by Mark Smith, founder of The Man in Seat 61, the rail travel bible. Infographic courtesy of a recent Amadeus study.