How can there be a price war?

I read the article on contact lens price war with great interest. How can there be a price war when Tesco can sell contact lenses cheaper than I can buy them?

Obviously we cannot be using the same suppliers unless I am being ripped off by my suppliers. If Tesco is buying from the cheaper European markets are CIBA Vision and B&L going to remain in business?

Thirty pairs Focus Dailies, Tesco: £20. Cost to me: £22.33. Six pairs PureVision, Tesco:  £56. Cost to me: £63.45.

Terence English
Rotherham, South Yorks