It is actually the other way around: they can afford to run at a loss or at no profit, and as such don't pay tax.
The "no tax" thing is really a byproduct of the actual problem. The actual problem is the US multinationals can and do run at a loss to kill off competition, because they can afford to. And tax aside: online retail has a lower cost base than bricks and mortar retail anyway, so even if an online retailer and a traditional retailer targeted the same profit margin, the online retailer could charge a lower price and so over time you'd see the high street wither (these are all obviously very general comments!).
But the large online retailers - well, Amazon - killing off markets because they can afford it is the biggest problem. The percentage of shopping journeys that start on Amazon is frightening. The global response is a decade too late/slow. Corporate income taxes are driven by profit. How do governments respond to companies who's policy is to run parts of its business at no profit for years on end?