Your working Lab is light compared to my friend's who are both show type. They weigh circa 33-35kg. It is a struggle for her to keep them in trim, especially as they are getting older and one is a couch potato. She had that one on a diet and it took about 6 months to get her weight down although the dog wasn't hugely overweoeight at the outset. Both dogs get considerably less food than the RDA - probably about 60% of the lower amount.
Owners so often make mistake of taking food packaging RDA's far too literally (myself prior included). 5 years ago I was studying charts on sides of kibble bag, measuring/weighing kibble portions & marking cups with masking tape. Now looking back I am mindful I was often doing so based on me proudly deciding which vague dog silhouette & description on packaging most closely matched my dog. (toy,small medium ,large & giant).
Owners are becoming more aware of obesity in dogs & that is one reason why more owners look at packaging for feed amount guidance.
As I type this both dogs are dozing on the couch....couch potatoes in the moment, however, a significant beach walk soon will change that.
Stating the obvious but like people, food ammount should ideally be based on relevant factors.
I accept it can be more difficult to find the correct feed amount in older dogs or dogs with mobility issues but much obesity is due to too much food or inadequate exercise...even in dogs DNA disposed to weight gain.
Must dash.......beach waiting !