Most drivers operate in personal threat-assessment mode, without regard to anyone else's safety or convenience. Same, regardless of whether they're passing, pulling into the road from driveways and parking lots, or cutting us off to enter a driveway or parking lot. Even when they see us they instantaneously go into personal threat-assessment mode, rather than taking a moment to rationally consider the options and taking an extra moment.
Crossing the center line to give a cyclist or pedestrian more room might put them into a head-on or clipping scenario with an approaching vehicle. That's a threat to the driver's person and property.
Not giving a cyclist or pedestrian a safe passing buffer, risking clipping or striking a cyclist or pedestrian? Little or no threat to the driver's person or property.
It's easy to guess which choice most drivers will take. Particularly considering the prevailing mindset of law enforcement and the news media toward injuries and deaths to cyclists and pedestrians, which regard anyone outside a metal cocoon as expendable in pursuit of driver convenience above all. A common example is when, after a cyclist is struck and killed or seriously injured, news media quotes law enforcement comments on whether the cyclist was wearing a helmet. It's the equivalent to the old "What was the assault victim wearing?" trope. No helmet = Asking for it. Here in Texas it's extremely rare for a driver to be prosecuted for killing cyclists and pedestrians. At worst they'll be ticketed for failure to control their vehicle or something similar There's no concept of personal negligence or liability. It's up to victims and survivors to pursue justice through civil courts, often with insurance claims dragging out for years.
I'm actually surprised by the number of drivers who not only give me plenty of room when passing, but go way overboard, driving completely into the oncoming traffic lane regardless of oncoming traffic. I only needed the customary buffer. Or they could have eased up off the accelerator for a moment, giving the oncoming traffic time to pass, then cross into the other lane to pass.
Fact is, most drivers are barely competent, even when they mean well and aren't overtly hostile toward the notion of sharing the common infrastructure with cyclists and pedestrians. They have grossly exaggerated opinions of their driving skills, presumably from watching NASCAR and way too much TV. Or they attribute dumb luck to delusions of skill.