Well, it is discrimination. Just select different countries of residence from the dropdown box and see how how rates can change.

Note that country of residence is not the same as nationality. I would imagine that a US national resident in, say, Turkey could be a better bet than a Turkish resident in Turkey. (Examples chosen purely to illustrate a difference without implying anything else.)

'Marketing', yes - an excuse to raise prices to unsuspecting clients while retaining competitive rates in major markets. 'Insurance', no, when comparing rates which don't include insurance - though this is more difficult when only insurance-inclusive rates are available in some markets.