plz can somebody explain to me a little bit about this context,

the concept of extra requirements becoming expected requirements overtime.
does it means, customers are buying quality products because is a good quality products and the demand is too high. i hope this is the right answer thanks.

It could mean that if your customer asked for an average and reliable car to get to work in and you give them a cadillac, they will expect a cadillac every time.
It is also called goldplating, giving the customer more than what they really wanted.