Why there is a today's need to consider 3 additional P's i.e. people, process, physical evidence in marketing mix?

People : People component reflects the very important role played by individuals in the provision of services. They are a very important element in the marketing mix -

Employess Welfare - Training - Motivation - Respect - Appreciation 

 

Process : Process is a set of activities that take an input , add value to the input and finally create an output. Process has recently been given much attention in the services sector. 

 

Physical evidence : The environment where the services is delivered must reflect in depth professionalism, expert organization, latest technologies, discipline, hygiene and reflect the corporate image 

I like your question, but not sure what you mean by "physical evidence".
Can you explain?

Semantics! The 4 P's understood correctly cover all possibilities. No need to try to outthink Phil Kotler. Anyone who says otherwise didn't do the original research and is trying to act important.

Physical evidence recognises & appreciates that business don't operate in vaccum but in an environment. Process- need to recognise & appreciate the fact that marketing is a process, its gradual & continuous or passive. People- need to recognise & appreciate the fact that businesses market & serve people (customers).

adding the other3Ps is in case of your business linked to a service.

nowadays all businesses are linked with service

in service industries these additional3p's are considered other then price, place, product, promotion.

because you provide services by people(staff) to people(customers). so people are the important part of7ps

then come process. any serivces you provide its provided through a process. for example if you have a clinic. a patient will first have an appointment for chekup, he will come see the doctor and pay for his fee. this is a simple example of process.

physical evidence.

lets carry the example of the clinic to understand easily. the interior of the clinic the equipment , its interior outer look etc are the physcial evidences.