Most editing software cares very much about colorspace. The issue is that users don't usually understand it (because it's very complicated), and even when they do, they often expect contradictory results from their software.

For example, Adobe Photoshop allows a user to set the working color space for manipulating their images. The vast majority of PS users probably want the results they've always gotten from the application, even before it had the functionality of setting the working colorspace. That means working in sRGB, even if it's not physically representative of how light works. In fact many of the blend modes, for example, are tailored to imitate linear light blend modes with non-linear RGB values. Screen in sRGB gives similar results to Add in linear RGB.

Fast forward to present day where many apps let you set the working space. Let's say a user thinks they want to use linear RGB to be more physically accurate. Suddenly nothing works like it used to! The Screen blend mode produces weird results! Contrast looks completely different! No amount of telling users, "This is what you asked for" will sell more copies of that software if it produces unexpected results.

And when a particular function works in a different colorspace internally, there's rarely a need for the user to know that. If it produces the results the user wants, then does it matter if it's HSV internally or HLS? or YCbCr? Or L * a * b?