The uncertainty specified by a manufacturer is not evaluated by considering a single sensor but by considering the spread across the whole production, determined both from sampling the production and by considering design parameters. 

Therefore, you should not interpret the specifications as "95 % of the time the uncertainty is within this range" but "95 % of the manufactured units have an error which is within the specified uncertainty".

Note also that it's not really true that the industry standard for uncertainty is given at a confidence interval of 95 %: it may depend on the specific parameter and on the manufacturer, and in most cases manufacturers don't report information about the statistics across the production. That is, interpreting manufacturer's specification frequently needs some guesswork (and don't assume a normal distribution of the error).

For instance, have a look at the data sheet of a popular temperature sensor, the [Texas Instrument LM35](https://www.ti.com/lit/ds/symlink/lm35.pdf), you can see that the manufacturer gives three different specifications for the accuracy: _typical_, _tested limit_ and _design limit_. In a design, forget about the typical specifications, because there's no information about which statistics these come from (are they a standard deviation, and expanded deviation, a mean, a median etc.? Who knows). Instead, the manufacturer reports, note (1), "tested Limits are ensured and 100% tested in production" and, note (2) "design Limits are ensured (but not 100% production tested) over the indicated temperature and supply voltage ranges. These limits are not used to calculate outgoing quality levels".