They aren't, and they create their own problems: the perfection of the seal they provide means that the air in the bottle has to be expensively removed before the stopper is inserted, and they are harder to extract than their natural competitors, although they do provide the expected satisfying plop when the bottle is opened.

ECONOMIST: Plastic wine stoppers

When the officer confronted him, the man sprayed the air with fluid from a plastic pump bottle that he had inside his jacket.

CNN: Subway checked for hazardous material; none found

When I left -- my stomach full and cheeks rosy from wine and the chill mountain air -- Kevlishvili offered me a water bottle filled with more of his heady, homemade grape juice.

CNN: Unearthing Georgia's wine heritage

As we approach the elephants, he takes out a small plastic squeeze bottle containing fine white ash and puffs some into the air, gauging the breeze.

WSJ: Walk With the Animals

Lying in the shadow of the active volcano Mt Tarawera, Rotorua Lakes is an unrivalled natural landscape where water is clean enough to drink, sweet-smelling air comes alive with native birdsong and fern-filled forests are as bright as a bottle of absinthe.

BBC: Lakeside treks in a geothermal land