Uncertainty is accounted for in the +/- tolerance of the dates given. It is accepted scientific practice to be extremely conservative and give the widest margin of error when citing an age.
The thing you have to accept is that time is relatively linear and time related coefficients are fairly constant. The the result is that quantification of time is mathematically derived and mathematically repeatable and reproducible.
We’re not referring here to merely the ‘time assumptions’ arrived at.
We are referring to the assumptions of the decay rate of the parent isotopes, the amount of parent or daughter elements in the sample have not been altered by processes other than radioactive decay, and also the initial conditions of the rock sample.
If these three assumptions are made, which they are in radiometric dating, it is impossible to accurately estimate the age of rocks. Hence the false ages ascribed to rocks that are known to be 200 years being dated 4.5 million years.