Why does opting out of one data broker not reach its buyers?

When I submit a deletion request to a data broker, the hundreds of secondary companies that already purchased my data are not required to act. Two arXiv audits published in 2025 and 2026 tested every California-registered data broker and found that secondary resellers go almost entirely untouched by opt-out requests. California's DELETE platform, which brokers must use from August 2026, puts the deletion workflow on first-party brokers but carries no cascade obligation downstream. My data continues circulating through the secondary market after I formally opt out of the source, with no technical or legal mechanism to trace and halt it.