Spaces work better than tabs because the code is always formatted properly. Code that is formatted improperly does not do what you think it does. This matters a lot when you have projects developed by 200+ developers with multiple millions of LOC. It matters even more when you have 3000+ developers working on many such code bases and they move between said projects with high frequency.
You cannot have your indent be two and me with 8 and have the code line up properly, especially when lining up complex if or math statements (where you may be using the level of indent to help with showing how the parens or operators nest). While you could argue "then split into multiple statements", I could argue "it's actually more readable as is". Subjective is neat that way.
Files that are being constantly updated because someone doesn't like someone elses formatting is dumb. Have a standard, stick to it. Fire the offender who refuses to play ball, problem solved.
Who prints code? Fine, let's say you do. Modifying the number of spaces per tab causes the issue I pointed out at phase 1.
Relationship argument makes no sense to me, sorry. Where the code lines up is what matters to me, not how many invisible characters appear between the beginning of the line and the first character.