Are the whole blossom falling off or is it only the yellow petals? if the whole flower is falling off at the knuckle then it isn't pollenated.

If only the yellow petals fall off then they might actually be pollenated and just need patience for them to develop.

That is one amazingly impressive cluster of tomato flowers though

I suffered through this same problem for two years, and then I discovered that I probably need to help with the pollination (I live in an urban area with a small back yard and little wind and few bees). See the link at the end. I'm getting about 80 percent fruit this year.

Here is a link that might be useful: pollinating tomatoes.

It seems to be just the flower petals falling off, so maybe I just need to be more patient. I have tons of clusters like that, so I am just oddly confused about the plants. In my mind, i'm thinking, "So... I should have 50 tomatoes growing RIGHT in this cluster.... Yeaaaah, ok."

And thank you for the link! I'll be sure to keep doing that whenever I am out in the garden!

First we need to know your location or at least your zone to speculate on the effects of weather and its relationship to the condition known as Blossom Drop. The FAQ on it is linked below.

Second, the name of the variety would be a big help. Some varieties are prone to doing as you describe, others are not. And your neighbor may be growing totally different varieties so they can't be compared.

Third, it would help to know if you have been feeding them and if so what as excess nitrogen can cause this.

Fourth, are there any signs of thrips or other insect pests?

Then please keep in mind that tomatoes are self-fertile, self-pollinating. They do not require insect intervention or anything more than a good breeze. Each bloom normally pollinates itself and often does it before the bloom even opens unless some other condition exists that neutralizes the pollen - primarily excess heat, humidity, and/or nitrogen.

Dave.

Here is a link that might be useful: Blossom Drop FAQ

It looks like a pollination issue. Also temperature is a factor in fruit development. Tomatoes need warm days and cool nights and consistent moisture. They also need bees and moving air (wind, breeze). You can also use a Q-tip or small paint brush to touch each blossom but nothing works like bees. If you can, plant a couple sunflowers near your tomato plants. They will bring in a continuous flow of bees to your yard and will take care of your tomato plants.

From the Pollination FAQ here:

Tomato blossoms are perfect, meaning they have both male and female reproductive structures. They are capable of pollenization without the aid of pollinating insects and without pollen from other blossoms.

Many of us who regularly save seeds bag the blooms to prevent cross pollination by the wind.. There is no way a bee can get to the blooms and yet they produce tomatoes.

Can a bee prevent tomato bloom pollination, interfere with it in any way? No. Do bees play any role in tomato pollination? Maybe a minimal, but wholly accidental one on rare occasions if he happens to wander by and there are no more interesting blooms around. Is a bee required for pollination? No.

Dave

Here is a link that might be useful: Pollination-Cross-pollination FAQ

What is the temp/rh?
Try misting or spraying water on the flowers. It's to keep them cool and bring up humidity to make it easier for the pollens to stick to the stigma.

They look perfect to me, you should see tiny fruit start in about a week to 10 days, the yellow flowers need to die, then you will see the tiny green fruit start. I am in Oregon, and my flowers are not even that large yet, so it takes time, depends where you live, but I see no polination problem. Since they are self-polinating, one trick is to simpy flick the flowers gently, if you are in a windy area, the wind will help polinate. You plant looks healthy to me and I have been growing them for 40 years.

That plant and its flowers look normal, to me.
Tomato fruits will grow very slowly, not like zucchinis . Just be patient, as already mentioned.

Too much humidity will cause the pollen to clump and
thereby inhibit pollination. Are your nighttime temps
above 55 F? That's another major factor in setting fruit.
So are temps above 90 F.