The U.S. is on metric; NIST defines and curates standards on the ISU and is a critical, founding participant in the GCWM. Manufacturing and engineering specifications (especially for the military) are usually ISU. It's just that commercially imperial units are still popular. Most people aren't engineers or scientists and so they don't think about this a lot, but marketing loves inertia.
The US is one of the original signers of the Metric Treaty, so technically we are metric. And it turns out that our common units are defined in terms of the metric system.
I manufactured plastic sheeting and all product was measured in inches, leading to a huge amount of conversion (24-3/8 sheet with +3/64 tolerance) and to me learning what a mil is (1/1000 of an inch). 10 mil plastic runs and stacks totally differently from 15 mil, and 40 and 60 mil take different amounts of time to cool and shrink, so there truly would have been switching costs going to meters (plus all the people who ordered 48x96 sheets, and rolls on 6-inch diameter cores, and so forth).
There's a lot of domain-specific units in use which aren't even imperial originally (fluid barrel, troy ounce/carat, ton of cooling, horsepower, AWG) that will stick around for a long time since they're used so frequently in finance, planning and B2B transactions, along with other imperial units that'll remain because they've taken on domain-specific uses (acre of land, fabric yard, bushel, mils) even when the engineers and logistics folks touching that same stuff are using SI equivalents.
There was a time in the mid-1990s when certain models of vehicles had both metric and imperial fasteners on them; made wrenching on them a major pain. But today, though, everything is metric.
You're right that consumer marketing is still toward imperial. I think it's just going to be a slow process of gradual weaning away as older people pass on. I'm personally of a "in-the-middle" generation (X) - I tend to be more comfortable with imperial units, but if metric is required, or I think it might be a better measurement to use (depending on the purpose), then I'll use it instead.
The U.S. is on metric; NIST defines and curates standards on the ISU and is a critical, founding participant in the GCWM. Manufacturing and engineering specifications (especially for the military) are usually ISU. It's just that commercially imperial units are still popular. Most people aren't engineers or scientists and so they don't think about this a lot, but marketing loves inertia.