I just want to emphasize two words: trust and freedom.<p>TRUST:<p>The primary reason why some solutions proposed by other comments around how we can use smart knobs, touchscreens with protrusions don't work is that we TRUST the physical buttons most. If you feel it registers, you know it surely registers. You can reach your finger towards the panel without thinking beforehand whether to increase or decrease the volume without fearing accidentally triggering other functions. In words of the WWDC 2018 presentation "Designing fluid interfaces", the thought happens WITH the motion. Why do people still use physical camera blockers when there are already plenty of software solutions available? Trust.<p>Smart knob-like implementations would not solve the problem. For really important stuff like the volume controls/mute button, we really need something that we users can <i>always</i> trust. The ideal implementation is probably only using them to control variables currently showing on the screen(like the touchbar!)<p>I read an article before about choosing keyboard to maximize typing speed. It mentioned that the more confidence you have with the keys the better. The experience of typing with unreliable and low-feedback butterfly keys on a VPS over the globe with 300ms roundtrip latency is beyond hell.<p>I have always hated automatic forced updates, even when they do not cause any performance or stability issues. With physical buttons, you know it is here to stay and can never change. However even we manage to make users able to navigate the touchscreen without looking or just with peripheral vision, who knows when it would change drastically tomorrow when it updates itself in the night? The crux is that with touchscreens, car makers would treat them, and the car, as a massive mobile device, but we users actually expect them to be like computers, or single-purpose servers.<p>FREEDOM:<p>The actual implementation is much much more important than the idea itself. The problem is simply too much freedom for the developer. JS and CSS animations/transitions, when used properly, can make the experience smooth while not being dizzy and annoying. But observe the current fiasco of "BEAUTIFUL" and "MODERN" web "DESIGN"s. The thing is, the limit of how bad incorrect executions can be, is probably more important the limit of how good it can be when correctly executed. We can have the fastest processors, screen with the fastest response time, and still some UI "designer" can make it feel slower than the Windows 95 on Intel Pentium, remotely controlled over the continent.<p>(Please excuse my poor english and bad writing skills.)