and there is still not a problem now, at least for Rabbit cards - at Silom and Siam stations Rabbit cards can be tapped at all entry/exit points, but now only some of the entry and exit points have inserts slots and some are tap only.
I originally thought this was for traffic management but yes it makes sense if there is a new style of single use BTS ticket - but nowhere have I seen any reference to new integrated single BTS/MRT integrated ticket
you may be confusing this with subway systems in other countries - eg London, Paris, Singapore, etc - where line interchanges are behind the ticket barrier and/or where different lines are run by the same public authority or company or common ticketing had already been established
but here in Thailand, for example on your preferred combined BTS/MRT trip from Thong Lor to Silom:
1) at Thong Lor BTS you buy a ticket from Thong Lor BTS to MRT Silom
2) you enter the BTS ticket gate at Thong Lor and travel to BTS Asoke where you then exit the BTS ticket gate
3) you cross the road and walk to the MRT station
4) you enter the MRT ticket gate at Asoke and travel to MRT Silom where you exit the MRT ticket gate
your ticket purchase at 1) is based on a single onward journey, but if you decide to then have a coffee or even see a movie at Terminal 21 how do you re-price your ticket as two separate journeys?
or if you are a 65 yo falung and qualify for a discount on the MRT but not on BTS etc
the originally proposed Spider Card solution was a stored value card that could be used to tap on/off on all BKK busess, ferries, MRT, BTS and ARL - each operator could manage its own fare structure and discounts and operators could make their own agreements as to what time period still qualified as a single onward journey
in the last few years, apart from repeated stories or continuing delays with the introduction of the Spider Card, I have still never seen any announcement of a single combined BTS/MRT or MRT/BTS ticket - or for that matter the availability of the Spider Card itself
but given justaguy's reports of developments on the Sukhumvit BTS line I live in hope - and will probably die in despair
bkkguy