Using this third party seller came up again. I understand that the UK might be a special circumstance for using them and maybe if you are buying a lot of tickets on different carriers and and you want them all on one app, then the convenience might make sense. But here is what I found in just one limited look. There may be circumstances where it works better than this so this isnt a "Dont Use" more of an observation to keep in mind.
I couldnt find a comprehensive list of the train companies that Trainline(.)com works with and that can be an issue if you dont know what you are not being made aware of. Apparently MAV is one that Trainlin(.)com does not work with. I checked Budapest to Vienna a fairly popular tourist route that is served by OBB, MAV and RegioJet.
On Tranline(.)com only OBB and RegioJet tickets were shown. So, a plus for Tranline(.)com as it will inform many for the first time that there is a third train company doing the route; and a negative as it omitted the Hungarian company (MAV) all together. Also missing was making it obvious that RegioJet usess a somewhat remote train station(s) and not the main city station. But thats not the end of the world either.
I assume the OBB ticket prices will match the OBB rail site, so I only compared the ticket costs on Tranline(.)com with the ticket costs on MAV for one random morning/early afternoon in July. MAV was cheaper in almost every instance and often substantially cheaper. That was because MAV always has more discounted tickets than does OBB (no, I dont know why). This might not be true for every date .... but again, you dont know what you dont know.
RegioJet is the cheap alternative between Budapest and Vienna. The quality of the equipment seems to be good, and they have updated it were its a little more like a flight with entertainment screens and drink service and ..... For this route they offer up to four levels of service. Leaving Budapest the RegioJet trains start at Deli, then stop at Kelenföld before going on to Vienna. Knowing which ticket you are buying is cryptic on both the RejioJet and Tranline(.)com sites. Look carefully.
9 July, Tranline(.)com shows a departure at 14:45 with two levels of service not very well explained. RegioJet shows four levels of service, Tranline(.)com does not explain the service of the cheapest ticket in enough detail so that you can look at the RegioJet website and be certain in any comparison. By price alone it appears that maybe the cheapest being sold by Tranline(.)com is the RegioJet "Standard" but if it’s the Low Cost option, and it could be, the ticket is more expensive with Tranline(.)com.
Tranline(.)com is also offering you "flexibility" without much description as to what that means for $1 extra. I cant find the same option on the RegioJet site. Also, if you want to travel Business (1st class) Tranline(.)com doesn’t make that offer; and the Business ticket is the real bargain on RegioJet. Some route times did show a business ticket Tranline(.)com.
This is not to say that there are not instances on some routes with some companies were the Tranline(.)com site might not have prices as cheap as the national company sites. I suspect they will. But the only way to know will be to look at trainline then look at OBB then look at the Czech site or the sites of which ever countries you are starting and ending in.
And there is maybe a good use for Tranline(.)com. If you don’t know what trains are service a route, maybe you go to Tranline(.)com and see who they show. Even then it might not show all as in the Budapest Vienna case, but there might be something revealed.
Since Tranline(.)com is reselling tickets one of those national sites will have the same price ticket as what Tranline(.)com does … so why not just buy them from the national sites and eliminate the middle man?