Baldness was not yet cool while Brent and I were studying horticulture at Cal Poly in San Luis Obispo back in the late 1980s. Nor were hairpieces yet tacky. Consequently, some middle aged men work toupees. As these men aged and grayed, their formerly well matched topees did not.
Hedges of Pittosporum tobira ‘Variegata’ are notorious for developing green sports (unvariegated mutant growth). https://tonytomeo.com/2018/07/04/horridculture-mutants/ Because gardeners do not prune these sports out, they become prominent green blotches in otherwise nicely variegated hedges. Pruning large blotches out would only leave big bald spots. That is why such hedges, as well as similarly blotched hedges of other variegated plants, are known as ‘bad toupee’ hedges.
‘Neapolitan’ hedges are a variant of that concept. They are not composed of formerly identical plants that later challenged their respective identities. ‘Neapolitan’ hedges are actually composed of different plant material that has been shorn together. They sometimes develop as feral plants grow up and into formerly uniform hedges. They are often composed of what should have been distinct plants within a well designed landscape, that were merely shorn collectively by ‘gardeners’ who simply did not care.
This hedge in a median of a driveway into a mall in town is a classic example of the latter. The landscape designer likely intended the deep green Burford holly, Ilex cornuta, to develop naturally as dense and low mounds between the more upright variegated holly olive, Osmanthus heterophyllus ‘Variegatus’. Apparently, it is too much to expect a well paid ‘gardener’ to figure that out. Fortunately, this particular ‘Neapolitan’ hedge happens to look good in this particular application, but would look better if the ‘gardener’ would replace the variegated holly olive that has been missing for years from the gap between two Burford hollies to the left.