Government inflation numbers don't work like that at all. They are based on the Consumer Price Index, which uses a market basket of consumer goods and services.
Yes, but all of them being commodities (what I said) is not the same as inflation only being accurate when someone purchases every commodity available in the marketplace (what you said).
Inflation of a portfolio of iPhones is completely different than inflation that an average American pays due to cost of living changes in the economy. You're cherrypicking a hypothetical scenario that doesn't apply at all to the example at hand, which is the average person's ability to pay for emergencies that arise related to living expenses.
Which includes blackbox modifiers like "hedonic adjustments". So if it costs you $800 to get a cast for your broken leg today as opposed to $400 a few years ago, but they claim the quality of the cast is twice as good, then they say there was 0% inflation as you are getting the same "value" even though its costing you twice as much to fix the same problem.
All of these are commodities. And every single product derived is based on commodity. Most commodities can be traded on commodity markets.