Light, and when it actually matters here
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For coffee, oxygen comes first
Light accelerates oxidation and it is not the main driver, and coffee packaging is usually opaque anyway because the barrier materials happen to be. The decision rarely comes down to light alone, and a clear container in a dark store room is not the problem people assume.
For green tea and matcha it is different
Color is the quality signal buyers use, and light-driven fading from bright green toward dull olive is visible and immediate. There the opaque container is a commercial requirement rather than a technical nicety.
Our bulk shelf is mostly not light protective
Only one of the 32 qualifying containers is, which is honest to say: this is a storage shelf chosen for volume, sealing and durability rather than for light. If light protection is the requirement, a store room that is dark is the practical answer.
Which is usually fine, because of where it lives
Bulk containers sit in back rooms and under counters rather than in lit display cabinets. The property where light mattered most was oils, and the reason was retail display over months; neither condition applies to a canister in a store room.
Except at a refill counter
Where the container is deliberately on display and often lit, which is the one case in this property where a clear bulk container is working against the product. Turnover usually saves it and it is worth being aware of.
The retail decision is a different one
A retail bag is opaque for barrier reasons that also handle light. A retail tea caddy is a choice, and for a green tea an opaque one is the better product even though it hides the leaf.