Maybe this helps answer the question of 'where did the bugs go', because windshields aren't as full of them today compared to 20-30 years ago.
There's a Wikipedia entry for that: https://en.wikipedia.org/wiki/Windshield_phenomenon
The answer to that is pesticides. There's still plenty of insects ready to smash into your windshield in many parts of the world.
I wonder what percentage is pesticides vs development? I currently live in an area(US) where a drive to the nearest city of size absolutely coats my car in bugs. US, mostly farmland(soybeans/corn). I wasn't here 30 years ago so can't say there's as many as then, likely not. But if it were only pesticides I'd expect the rural areas to have less bugs than the more developed areas...
As someone who has made many interstate trips through Australia's farmland, I can say that over the decades there's definitely been a drop in windshield splatter. It's unsurprising that pesticide deployed at scale reduces bug populations. Even herbicides which aren't intended as insecticides have limited product advantage to being bug-safe (apart from pollinated crops... and even then). Some aren't even human-safe. An extreme example is paraquat, that while being a herbicide, is irreversibly deadly to humans^ when consumed even in tiny amounts.
^ Obligatory Chubbyemu: https://www.youtube.com/watch?v=0VtUGoGZtI8
I would lean towards the urbanization of the land as well. I rarely get bugs on my car in the city, but as soon as I head out to the country at night my car is covered. I had to stop at a gas station back in May not for gas but just to squeegee the windscreen so I could see again.
wow this would be a neat twist if true - we all defaulted to the negative explanation of having killed them all where a much more positive explanation might be that we're no longer luring them to their deaths at the leading edge of automobiles?
I guess it is most likely some combination of the above, but if there's any evidence it would be a neat reframing
Colorado: "Insect biomass declined by ∼47% and abundance declined by ∼61.5% over the last 35 years."
https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2...
Germany: "More than 75 percent decline over 27 years in total flying insect biomass in protected areas" https://journals.plos.org/plosone/article?id=10.1371/journal...
Puerto Rico: "dry weight biomass of arthropods captured in sweep samples had declined 4 to 8 times, and 30 to 60 times in sticky traps." https://www.pnas.org/doi/10.1073/pnas.1722477115
I think they just all collectively got tired of hearing my dad's punny about "it doesn't have the guts to do that again" any time a bug squashed on the windscreen.