I would bet the influence is not significant to you — you would get the same product for the same cost either way in most cases, but it is significant for the brand you end up arbitrarily choosing.
I simply mean that it makes no difference to you whether you buy your gas at Shell or Chevron because it costs the same and you get the same product. But it makes a difference to Shell if you buy your gas at Shell.
Since it is inconsequential to you, you don't care or notice the impact.