Why is time so important in services?

Why is time so important in services?
Your question is a little vague but I think you're asking about the importance of the time of the person performing a service for payment, example: housekeeper, technical support, customer service call center employee, etc.

From the perspective of the service provider:
Different from selling an actual product, in providing a service what someone is actually selling is their time. Time not spent rendering service to a paying customer is time wasted in the mind of the service provider. Literally, time is money.

From the perspective of the customer:
When a customer hires someone to perform a service, it is almost always beneficial to the customer to have the service completed as quickly as possible; whether it's to save money on paying an hourly fee, to meet a deadline, or because the service being performed solves an existing problem that could be costing the customer money or simply be a hassle for the customer like having a computer system go down.