Many roles we classify as trades are becoming increasingly difficult to distinguish from the roles we typically associate with college education. This is partially due to the fact that they are increasingly technical, partially due to the fact that trade schools are offering training and certification in fields that were once exclusively in the purview of colleges, and partially due to the fact that our jobs are becoming increasingly cross-pollinated (mechanics using augmented reality, electricians building custom electronics, plumbers using GIS mapping, etc.).
This makes defining the idea of a "trade" much more difficult. I think for the purposes of clarity, we should find some sort of line that distinguishes trade education from liberal education. I think the best way to do that - and this is obviously just my opinion - is to classify as a trade any work that doesn't directly question and debate theory or, put another way, any work that almost exclusively implements theory. So in this definition, you would obviously include the existing trades, but it would also include things we typically associate with college education like nursing, most software developer roles, therapists, architects, most engineers, etc.
I think the reason most of those roles are task-oriented (performing a function according to outlined requirements and expectations) but still trained at the college level is that they arose from more theory-oriented areas of study but never made the shift away from college when they entered mainstream, non-theoretical application. For instance, computer science was born from mathematics, but at this point, the average software developer doesn't need a PhD level of understanding in math to do their job at all. Nursing, similarly, was born from specialized forms of medicine, which was always a university-level field, but in recent years is shifting into 2-year programs and a more trade-like structure at the entry-level.
When you think about things this way, it suddenly makes the stigma against trade school seem silly. Most of us are doing trade work anyway. I write software, my friend wires buildings, my other friend does plumbing. We are all trade workers because we are ultimately just implementing theory, not discussing and questioning it.
This should also inform how we judge education. I have a couple college degrees, but I do not have what I would call a liberal education. I have not trained extensively in philosophy, law, theology, art, etc. My education is exclusively applied topics like finance and software. When I judge the quality of my own education experience, I am using different criteria than I would for someone that has training in English, history, or law. Their standard for "success" in the context of education is primarily defined by whether or not they take a role of social leadership and influence in their community (education, politics, writing, etc). Mine is different because I judge my success on whether or not I deliver a completed product in the context of my technology job.