Let's be honest: most people simply don't care who they build with,
Exactly. Then I say "doesn't matter," i.e. I take the one the others in my row choose.
What do you do if the first person comes and says: "I’m building individually!"
That option doesn't exist. He can only say "with X," then he can only be assigned a plot located between/next to other "with X" builders; or "with Y," in the same way; or "doesn't matter" (which increases his chances of allocation and he has the surprise whether it will be an X or Y row).
Already placed an ad twice in the newsletter - no response received.
I didn't mean for you to look for joint application partners in the newsletter. The mayor should write in: a call to individual applicants to report with whom they want to build so that the lottery can be supplemented with this information.
So again my example: I ideally want to build on No. 10 and have said "doesn't matter" or "Huber." The applicants for 9, 11, and 12 want to build with Huber. Then it fits. Or I said "Meier." The applicant for 26 said "Meier," the applicants for 25 and 27 said "doesn't matter." Now I get plot 28 in the row 25 to 28, which Meier builds.
So I wanted a middle house on 10. If I say "doesn't matter" or coincidentally (coordination is not possible here because no one responds to my search ad) the same as the others in the row 9 to 12, then I build on 10. If I say something different, I have to slip into another suitable row and now build with my preferred provider, but an end house on 28.
The municipality has (for the individual applicants) in my example five lottery classes: for "doesn't matter / I join," for "Huber," "Meier," "Häberle," and "Pfleiderer." Häberle may well be a prefabricated house provider for all I care - the main thing is one row = one provider with jointly planning builders.