Answer: Aren't gardens just amazing!
There are just so many variables at work in the garden, it is hard to predict what will or won't happen due to any one isolated act. While your gardens may be close together, their conditions may be wildly divergent depending on soil conditions/improvements, watering methods, exposure and air currents, varieties grown and even timing for transplant and add to that the variables of seedling and pre-transplant care... Often stress at a certain stage of a plant's early development can have consequences far down the line in terms of flowering and fruiting!
Then of course there are the uncontrollable things like incomplete pollination due to rain or blossom drop due to high temperatures or drought stress or even failure to blossom due to something out of your control such as a cold spell at the seedling stage....
If there is widespread and frequent use of indescriminate broad spectrum pesticides in your neighborhood, I suppose there could be a pollination problem. Many native plants as well as cultivated fruits and vegetables are pollinated by insects, so it is worth pondering the effects of insect eradication, particularly if they are in an area where they are unlikely to contact people; however the removal of a paperwasp (I suspect) nest would be unlikely to affect all of your plants. Other environmental factors are also critical -- an early dry spell or late frost can zap a cherry crop for instance and rootbound transplants may never outgrow that early stunting.
Tomatoes can be touchy with regard to everything from soil moisture to night time temperatures, as can peppers. I am not sure about the cucumber vs. zucchini problem excpet that some varieties can take longer before they come into production and that zukes do produce male flowers before they begin to produce the bearing female flowers. (So you should have zukes soon!)
Having said all that, you can certainly try hand pollinating if you suspect this is the problem or if you want to experiment a little.
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