Why do they do this? The problem is so obvious that you'd reckon they're doing it to deliberately annoy users.
The problem doesn't stop there, the lack of gain with Bluetooth is notorious. Almost every Bluetooth device I own has insufficient gain, franky it's a damn nuisance. The audio in the two sound bars that I own is so low on some audio material that I'm thinking of pulling them apart to see if I can find an op amp and increase its feedback resistor to obtain more gain. I should NOT have to do this.
Let me give you an example, the audio levels on many YouTube videos can be all over the place. Often the audio can be 6 to 10 dB below what it ought to be, thus it's impossible to listen on a laptop's speakers, especially so when one is listening in a location where the background noise is high.
What's wrong with the designers who design this digital stuff, don't they ever use the equipment themselves?
Haven't they ever seen a traditional radio or HiFi where the volume potentiometer is off at the 7 o'clock position, 12 noon is the maximum volume with a nominal one volt input signal or a radio station that's using normal levels of modulation, and the reserve gain is the range from the noon position to the 5PM one?
Do I have to say it again? The reserve gain is for when the input signal is lower that it ought to be. The world is not ideal, audio signals can be far from ideal—even from high tech companies like Google.
Occasionally help comes along, VLC has settings that allow the gain to be set to over 100℅ but I've often had situations where even VLC hasn't had the necessary reserve.
I've come to the conclusion the designers and programmers of this digital equipment haven't a clue about how ordinary amplifiers work. Or they have never taken the trouble to find out. They just assume a 16-bit input has 65536 levels and that's the range. Full stop! They never give consideration to what happens when the peak audio input covers perhaps less than one third that range of bits.
To get enough volume I've even had to use the audio equalizer, that's when one has been available, and often there is not. To get the extra gain I slide all sliders to maximum. Having to do this frequently is an ergonomic nightmare.
This is what happens when the arrogant digital world is too prowd to take a leaf out of the analog world—the world that managed to get these issues right about a century or more ago.