Funnily enough I drove down that 90 mile road two weeks ago. Here's a piccie I took with my drone (video won't upload):
View attachment 373516
It's a straight road. No bends or curves. The higher the drone went, the further I could see. Funny that. And if I get the drone to look out to sea at around 1,000m up (well away from civilisation where there may be restrictions) then you can see ships in the distance. But as the drone drops they dissapear over the horizon.
Why do you think that happens?
Oh, another thing. I've now driven across the continent north to south and east to west. The difference in distance is a few hundred kms. Your flat maps show Australia about 5x as wide in width compared to height.
Your flat earth map is very wrong indeed.