Anonymous participant To add, the officer at entrance to the fast track only checks on your eligibility to utilise the fast track, such as elite visa, paid fast track services etc. The officer at the counter will not bother how you enter the fast track lane. At least for me.
because of visa free agreement between both countries. So a Singaporean passport holder should not be paying any fees accordingly to the agreement, however Thailand would like to charge for the visa. So both countries are still ironing out the details.