Bitcoin wants to waste resources for a specific operation - which is to prove that work was performed. The other aspects of bitcoin, such as sending transaction

Bitcoin wants to waste resources for a specific operation - which is to prove that work was performed. The other aspects of bitcoin, such as sending transactions and validating transactions, have no need to waste resources and are designed to be efficient. A good analogy is password hashes. If you have a hashed value, it is expensive to find the original input. If you want to check that an input is equal to the hashed value, that is a cheap operation.