detector rail can't output redstone signal ‘HIGH’ while cart passing.
unless player ride this cart.
but powered rail can drive cart. (onMinecartPass() is ok)
should I use onMinecartPass() to detect cart from TC?

Do you talk about the Minecraft Vanilla Detector Rail? That works fine here.

okay good news, it was kinda hacky, but this should be fixed as of 94f725c

yeah... only loco can be directly detected
passenger car requires passenger
or feight car requires feight？

The trains and rollingstock are heavily modified minecarts, so some functionality does tend to be off.
Especially in the hitbox/collisionbox area, which is probably what's messing with it.

onMinecartPass() will be more reliable.

I see, thanks.