i have noticed this since quite some time now and communicated the same to people around me. Shell is definitely overpriced.
In its 0w20 variant, shell charges a premium of more than 800 over its competitors i.e. caltex, total and zic
There are numerous customers who use shell semi synthetic which is quite overpriced. pso 5w30 and total 5w30 both sell for less and are fully synthetics. iguess even zic 0w30 fully synthetic sells for less than shell 5w30 semi synthetic