Omo in France is the same product range as Surf in Ireland and the UK. They didn’t or currently don’t use Surf as a brand in the French market.
Also the French Unilever Persil range has no equivalent here. It’s a bit of a confusing one too - sort of natural scents focused but also sort of a second tier value brand that never quite makes its mind up.
I think tbh the second tier idea makes little sense these days as supermarket own brand are extremely good value and very competent products. Back in the 1980s that wasn’t really the case. Supermarkets here were full of very very cheaply own brand detergents, mostly made by McBride that were often very poor performers.
We used to have “Yellow Pack” in the Quinnsworth and Crazy Prices (yes, that was really a name of an Irish supermarket chain in that era …) which became synonymous with “cheap, basic and probably rubbish …”
These days the supermarket own brand household products are in a whole different league and many of them are definitely up the with mainstream brands in terms of how they perform.
So I think for the likes of Unilever or P&G etc making a second tier brand became a bit of a pointless exercise, as you were just competing with the store brands and their overheads will always be lower, and they’ve effectively no marketing costs.