I avoid these devices for the privacy concerns and also the generally poor security of IoT devices. I hate to sound like a luddite, but i really abhor these devices and how hard the tech companies are trying to foist them upon us as "the next big thing".
Either Apple/Google/etc and granulize the permissions such that things like "boolean: user is in vehicle at speed" are addressable separately (possible but unlikely) or such knowledge comes with a cost - the app knows where you are and have been.
Same applies doubly for "noise it has heard".
Consequently my decision is: no assistant, thankyouverymuch.
How will it learn to compare all these different environments? ML obviously; which pretty much entails leveraging the consumer data to provide a better product. The cost of usable, voice-driven assistants is giving up a vast trove of personal data and abandoning the concept of privacy completely, just so I can order some paper towels from an Internet of Shit connected device instead of walking three blocks to a store.
Your position is akin to a Louis CK joke(not offense meant): "Oh boy! I hope he doesn't do what he's going to do!"
Whether you're considering voice interfaces, connection speeds, machine learning, web development, phone battery life, or whatever.. things are trending towards the better. Sometimes it's steady improvement, other times it's punctuated. Either way, the floor on what we can considering is always increasing.
I think security is getting better but what we see now are the consequences of years of poor decisions. It's the post-Christmas credit card bill.
While not quite what you meant, Firefox is frequently bloody awful now and it used to be quite usable :)