I get laid off and suddenly I'm poor and am weighing optins. And I'm American.
I like to compare it with donations. If you get a USD donated, that is the same USD regardless of who gave it. Right? Right?!? Either way you don't know how heavy the burden is on the person who donated. You probably don't care. But it matters to the person who donated.
A $1 fee is fine for Indian software developers and it kills the spam. If it's a greater burden for people in India than the US, well, not all solutions are perfect, but some are useful.
Also, no it wouldn't kill spam. The spam would be moved to pwned machines where the owner would suddenly have an incentive (financial) to fix the system, if they know.
What remains is people who would be so rich that $1 means nothing to them. Ie. white collar criminals who are already rich enough to not care.
This is very noble in theory, but in practice you're not going to get many high-quality PRs from someone who's never been paid to write software and has no financial support.