Why don't all roller coasters have seat belts?

Some roller coasters have seat belts, little pieces of fabric that keep you strapped into the ride. Other roller coasters, ones that seemingly look very similar, don’t have seat belts. Why? What purpose do these belts actually serve and ultimately: why don't all roller coasters have seat belts? TWITTER:   / coasterbot   DISCORD: http://discord.coasterbot.com​​​​​​ STORE: https://coasterbot.com/store​​​​​​ PATREON: http://patreon.coasterbot.com​​ Credits: Coaster Studios:    / coasterstudios   JohnYChen:    • Flying Turns Roller Coaster On Ride  Ultra...   ElToroRyan:    • The Incredible Hulk Coaster Off-Ride Video...   00:00 Introduction 00:34 What do seat belts look like? 01:08 Why do some roller coasters have seat belts? 04:18 Why don't all roller coasters have seat belts? 07:12 Conclusion