Cabbie turns in $187,000 found in back of his cab....

[blooz]

I agree that "doing the right thing" should be enough, without reward. Not that i would turn down the hundred bucks if it had been me.
The Seeming paltriness of the reward is in keeping with the character of a person who would be stupid enough to carry that much cash around in the first place, and then forget it in the back of a cab, or anywhere, in the second place.

I find the whole thing about the inheritance coming to him in cash rather bizarre.