There was a strange reason behind to the question why Raj Kapoor used to call his younger brother Shashi Kapoor ‘Taxi'.
It was the time when Raj Kapoor had planned to make one of his iconic and most talked about film Satyam Shivam Sundaram, which told the difference between physical love and spiritual love.
When many actors were queueing up to perform the lead role, Raj Kapoor thought that only Shashi Kapoor is appropriate for the role of a male protogonist. But Shashi Kapoor was a demanding actor of those days, all the top directors wanted to cast him in their films and Shashi was committed with 4 to 5 filmmakers.
Also Raj Kapoor wanted dates in a bunch and with a condition that when Shashi would work for Satyam Shivam Sundaram he would not work for any other film during the shooting of this film.
So Shashi had to work round the clock, he would do 4–5 shifts a day and sleep in a car, his own or in a hired taxi .
To Raj Kapoor, Shashi Kapoor always looked like “running away in taxi” and so he gave him the nickname ‘taxi'.
Raj, out of frustration that his younger brother is not having enough time for his film Satyam Shivam Sundaram, he called him as “Taxi”.
Raj Kapoor would tell Shashi Kapoor that, “ You people aren't artists. You are all taxis. Someone puts your meter down, you go there. Then someone else puts your meter down and you go there.”
For one more reason Shashi got this nicknane that is, he was known to pick up or drop any of his co-actors in his car or taxi as he travelled regularly between places and shifts for shooting for his films.