The term 'quality' in a business sense means 'fitness for purpose'. A supplier supplies a quality product when it exactly meets the requirements of the end customer.
When an airline provides a first class premium service to customers who are delighted with the service, then they have provided a quality service. Alternatively when a low cost, no frills airline provides a bargain basement flight to a passenger and the passenger is satisfied with the service - then this would also be considered a 'quality' service. You can see therefore that quality can be achieved at all levels of the price spectrum for products and services.
What businesses are interested in is achieving total quality systems. What this means is that they concentrate on quality at every stage in the production process. Everyone that works for a firm deals with internal customers, many also deal with external customers. Take for example, the case of a product that goes through 3 processes before being sold to the end (external consumer):
Teams of workers are involved in carrying out the 3 processes. Each team should be responsible for guaranteeing the quality for their process. In this way there should be no defects or waste from the process - enabling total quality management.
Many companies today operate a system of continuous improvement whereby teams and individuals are constantly seeking to identify small step improvements in production methods so as to make quality improvements to create even more satisfied internal and external consumers.
Today total quality management is more important than end of production line quality checking, to ensure the highest level of customer satisfaction and wherever possible 'zero defects'.