there's usually a long lag between a drop in the price of an input and the eventual impact on the price of the outputs, because part of the effect is mediated by the adoption of innovations that use more of the newly-cheaper inputs and less of the still-expensive inputs
to take one example, the last time we got access to a major new source of energy was something like watt's steam-engine in 01776. one of the effects of this was the widespread replacement of steel cans (which hadn't been invented in 01776) and glass bottles with aluminum cans in the 01970s, 200 years later. another was the replacement of travel by ship with travel by air, also about 200 years later. the delay is because many intermediating innovations were required, for example, in the aluminum-can case:
- the discovery of electrolysis;
- the discovery of aluminum;
- the discovery of canning;
- the hall–héroult process;
- improved aluminum alloys that permitted the use of 100μm-thick cans;
- the invention of deep drawing;
- epoxy liners that made aluminum cans chemically stable to acidic contents such as coca-cola;
- long-distance trucking which increased the cost imposed by heavier glass bottles.
