and greasy sons assist him (it's a family filling station) (11-12)
They're working together! What's more loving than that?
(Embroidered in daisy stitch with marguerites, I think, (31-32)
Someone took care to make an intricate pattern on the doily. And we're betting it wasn't the greasy sons. Embroidery takes time and care. For someone to make this doily, they have to have cared, at least a little bit, about the space it was going to call home.
Somebody embroidered the doily. Somebody waters the plant, (34-35)
Even though this place is kind of a dump, somebody's putting at least a little love into it.
[…] cans so that they softly say: ESSO-SO-SO-SO to high-strung automobiles. (36-39)
The way Bishop puts it here, it seems as though the oilcans love the cars. And suddenly, there's a tenderness added to the scene.
Somebody loves us all. (40)
This says it all, don't you think? There's love for every person and thing, even in a cruddy old filling station. This definitely rings out as the Big Message line. The question is, is the speaker being sarcastic here? Or just plain old corny?