I have observed so many times that anytime a pastor prays in a public bus, people yell amen. Of course that is only when a particular prayer is said.

At the beginning of every prayer, people seldomly respond due to many reasons. But when the prayer man says "Oh Lord, let not this bus have accident. Help the driver to steer the bus. Let everyone get home in peace". Whoa! The whole place is turned to a church not minding if anyone is disturbed. Some pastors make their money from the mini crowd

The crux of the matter is people respond the prayers because they fear death. No more, no less.