no one has "observed" evolution in the same way we observe a snake molting or a comet
Depends on how you define "evolution". In the simplest , literal sense, even speciation is not required for evolution. Just an appropriate change over time is enough.
In the most detailed sense, biologists do not even agree as to the exact mechanism of evolution. So observation is out of question.
So while talking about science being a formal method, learn one of the first steps - not using ambiguous words without precise formal definition. A whole field of study isn't "observed" typically - specific phenomena of it are. Speciation has been observed in fruit flies. Measurable reproductive nucleic acids change has been observed with bacteria. "Evolution" is each of these, all of these, or more.
Similarly, no one has "observed" a comet precise to picometers. Nor has anyone observed the role of all the molecules involved in a snake's body while molting.