I would imagine the difference has something to do with the obviousness of the claim to others. No sane person denies the existence of cars or buildings so there is no need to insist to people that they exist. If someone did insist cars or buildings didnt exist I would be pretty tempted to insist they did, wouldnt you?
I imagine that is what its like for someone who finds a god belief obvious, hence some of them feel the need to insist.

why does anyone insistently communicate that some form, typically their personal brand, of god or gods exists? — whollyrolling

Tribalism might be part of it.

No one gets on their keyboard or walks down the street of their city insistently communicating to everyone that automobiles or buildings exist, so then why does anyone insistently communicate that some form, typically their personal brand, of god or gods exists? — whollyrolling

Evangelism is the advertisement of religion. Humans encounter 4,000 to 10,000 ads a day, whether it be cars, or buildings. The advertisement benefits them, allows the people to know about their investments and proliferates their money growth rates. For religion, it expands themselves and seals the belief of other people, but still, it benefits them.

The disparity whether a deity and something humanly or perceivable exists, is simply because the existence of a deity is sealed unto argument; hence why it's very controversial and has been discussed monotonously since the ancient ages to the renaissance. The fruits for the existence or nonexistence of a deity is life-changing, it decides the epistemological and metaphysical principles of our existence: meaning, purpose, and all sorts of ontological reasoning, thus they are really different.