I don't agree with this at all.
For context, I'm a woman, an ex Tesco employee and I used to do a lot of cover in our store warehouse. It is EXTREMELY dangerous work at store level, and significantly more so at distribution level. Unloading products from a cage onto a shelf in store is absolutely not the same thing as running/staying on top of a large, busy distribution centre that needs to sort deliveries for all stores within their 'group'. To say the two roles are the same and demand equal pay is laughable - one comes with significantly higher risk factors and extensive training, especially in health and safety.
Distribution staff are specially trained for their roles in ways general store assistants are not. Store assistants could not walk into a distribution centre tomorrow and instantly learn how to do the job of a warehouse operative. The training and sign offs for operating the heavy machinery alone takes time and skill. They are completely different roles! I cannot stress that enough. I challenge any Tesco store staff member to do a week at a distribution centre, and still come out thinking they are entitled to the same level of pay for sitting on a checkout. I seriously doubt after a week they would have cleared much of their initial training.
It's got heehaw to do with gender, and everything to do with different job roles and 'danger money' premiums. Warehouse staff are at MUCH greater risk of injury and are tasked with safely and securely storing and loading every single product that comes through the back door. They sign and take responsibility for every delivery. It is no small job, and to suggest warehouse operatives are doing the 'same work' as shelf stackers and till workers is bloody ludicrous. I'm not saying one is more important than the other, but one requires experience/training/working in a more hazardous environment, and these factors ultimately command a higher rate of pay, and rightly so. This lawsuit may as well be asking for GA's to receive the same pay as team leaders and managers, despite not being trained for either role.
No store in my group discriminated against women for warehouse roles while I was there. It was simply a case of the best person for the job got it - some women, some men. I knew loads of women who worked at our distribution centre, and they earned the same pay as their male colleagues. Tesco pay their employees equal money for the level/role they are at/doing.
A nurse working in a state penitentiary will be on a higher hourly rate than a nurse of the same level working in a general hospital. The risk to injury/life is increased, different skills and additional training are needed, and companies will often balance all of this by paying staff a little bit more. A heavy goods driver will earn more than a delivery driver in a standard size van. You'll pay more or less for a haircut depending on the level at which your hair stylist is at. An office based project manager may receive some sort of 'hazard pay' every time they need to work on site. This with Tesco is no different. They are not stopping women from working in their distribution centres. If people want to earn that level of pay, they need to be willing to work in the environment paying it and gather the relevant skills and experience to do it.
Equality is not a pick and mix deal. It should be equal pay for an equal role. These roles are not equal, and as such, one does pay more. There is absolutely nothing preventimg these women from applying for higher paying roles within the distribution centres, or elsewhere with better pay. Better pay usually commands certain expectations, however, and if you're unwilling to work towards those expectations, I'm afraid that's on you.
The sexism and workplace gender stereotyping I used to experience at Tesco for working shifts in the warehouse was insane. But guess what? It wasn't men making the comments, it was women, young and old. No male colleague of mine ever treated me like some delicate little flower. My vagina never factored. I was met with general horror and cats bum faces if I ever suggested to female colleagues that there were overtime shifts going in the warehouse if they wanted them though. They didn't want to do that level of work or go through the necessary training. It was a 'man's job' 
I would put good money on these same women jumping right on this bandwagon, demanding more for a lesser skilled role, one that is ultimately much safer and more 'woman friendly' ... apparently 
I am right behind any woman trying to close the gender pay pay gap when in an equal role, sitting on equal skills, experience, etc. This is not the case here though.