The bus conductor charged me a full ticket for my backpack! Was I scammed?

This is actually not a scam, it is standard procedure, though it feels unfair.

The Rule: Standard Sri Lankan buses have no luggage hold. If your bag occupies a seat (or is large enough that it could occupy a seat), you must pay for that seat.

The Exception: If you can squeeze your bag onto your lap or shove it under the seat (impossible for 60L backpacks), it's free.

The "Front" Space: Sometimes you can stack your bag on the engine box next to the driver. If you do this, they might charge you half-price or nothing, but it’s up to the conductor's mood.

Alternative: Take the Highway Buses (Air Conditioned). They have proper luggage compartments underneath, and bags are free.