They do. The text is somewhat misleading and not properly explaining that.
All hash functions have collisions. But from a cryptographically secure hash function we expect that nobody is able to find such a collision. They exist, but the computational power to find one is not available to humans.
This is wrong. There is something called a perfect hash function:
https://en.wikipedia.org/wiki/Perfect_hash_function
>a perfect hash function for a set S is a hash function that maps distinct elements in S to a set of integers, with no collisions. In mathematical terms, it is a total injective function.
They are very handy for hash tables with constant worst-case lookup time.
In the more general case, for a hash function with n bits output, the pigeon hole principle demands that we have a collision at least every 2^n inputs.
> Also, it should be computationally infeasible to find any other word which also hashes to '...'