I use to own a couple franchise of grilled chicken, won't say the name of the brand. A typical bird should be 1-1.2 kg, so I had to weigh every bird head office sent us, if it goes below 1kg it gets rather small.
Problem is most stores are manager run, owner don't step in the stores, don't care what size the birds are.
90% of grilled chicken places now, oven there birds in a steam oven, then finish them off on the grill for 6-7 minutes. Can't compare to a bird that's been fully flame grilled. You get a rubbery taste and often allot of marinade washes off from the steam.