Why subtract 1 from range?

Codecademy Last Section instructions:
“You can use range() in your list comprehension to make i go from 0 to len(new_prices) - 1.”

Code Last Section:
cuts_under_30 = [new_prices[i] for i in range(len(new_prices)-1) if new_prices[i] < 30]
print(cuts_under_30)

Question:
Why subtract 1 from range?

We don’t. The description subtracts 1 to denote a range. We would not subtract 1 in the range function, itself.

[new_prices[i] for i in range(len(new_prices)) if new_prices[i] < 30]