Simple. Hotel has customers and a customer will never wait 
for things. They have to be ready to him handy. Thats why 
they have a overhead tank with water heating 24*7. 

Where as in home its all our schedule and we can do the way 
what ever we like (:) you can't blame anybody)

Ofcourse these days getting 24*7 hot water is a quite 
common in home's too..

In home systems, the water sits a while stagnant in the
pipes until you open the valve to let some out.  It takes a
bit of time for the hottest water to reach the open valve. 
Many commercial buildings have a recirculating hot water
system in which a small pump circulates the water from the
hot water tank, out through the system and returns it to the
tank.  City water pressure still forces it out the tap when
you open the valve, but since the water is never stagnant,
it never cools off in the pipes, and so it is always hot
when you open the tap.

I think the answer lies around probability rather than
customer's unwillingness to wait.

At home, the plumbing system sits mostly idle, so water in
pipes looses heat.  Since at home you have quite a small
number of people, probability that someone used hot water
recently enough is very small.  Hence, usually you have to
wait for water to make its way from water heater to your faucet.

In hotel, number of people utilizing the plumbing system is
much larger.  As the number of users of the system
increases, so is the chance that it was used recently
(basically the Infinite Monkey Theorem). For large enough
hotel occupancy, use of water system becomes nearly
continuous or at least frequent enough to prevent
substantial loss of heat in the pipes.  Hence in large
enough hotel (with large enough occupancy rate) hot water
would be more readily available.