In a video of ADVChina on Youtube, the speaker recommends using a VPN in China for various reasons and to register using his referral code.
He says that there are various practical uses including "You can also buy cheaper plane tickets by browsing different countries." and shows a screenshot of a flight website called KAYAK, with VPN software moving his country to Italy.
Is it possible to get cheaper plane tickets using a VPN in this way? I have never heard of KAYAK, but if I use something like Skyscanner, is it common for the price of a ticket to be different, depending on the country of origin? the IP of the user?
Is it because of different taxes in different countries? So, could it be illegal to get discounts like this? Or is there an airline pricing strategy to charge different amounts depending on the country of purchase?