Not a visa question, but a motorcycle rental guy by cnx train station wanted to keep my passport for duration of rental. This...IS illegal, right?
TLDR : Answer Summary
The general consensus among expats is that it is not illegal for a motorcycle rental shop in Thailand to ask for your passport, but it is not advisable to surrender it. Many commenters suggest providing a cash deposit instead of handing over your passport, as retaining it could lead to scams or extortion scenarios. It's recommended to keep a photocopy of your passport and to ensure you have your original passport on you at all times while in Thailand.