When inconsequential, capitalization gets messed up all the time, and the mistakes are overlooked: everyone understands that a weight labeled “10 KG” has a mass of 10 kg, but it’s better to get used to good practice for when it does matter. Thankfully, the “M/m” mistake of 9 orders of magnitude is usually caught by humans before it gets out of hand: you wouldn’t order 1 mm³ of wood instead of 1 m³. Very few quantities span 9+ orders of magnitude, for instance 10mΩ and 10MΩ resistors exist quite commonly, and you can imagine one being mistaken for the other with people copying each other’s handwritten component list. However, I’d bet that the bit/byte dichotomy confuses hundreds of people every day so we better make that clear by not breaking rules.
BTW, the word is “megavolts”, not “MegaVolts” or any other capitalization, similarly “byte” is correct unless at the start of a sentence, with title case, or in German, and perhaps in words like “MByte”, which I discourage in favor of the full form or complete abbreviation.