Yes I agree the chance for discrimination increases with any restrictive process. So vaccine passports, well who knows, there's also the worry that these "passports" turn into "national ID" cards. Something the Coalition has been pushing on for a while, which starts to encroach on police state technology. In the US the actual amount of restriction from businesses is low, it really serves no purpose other than block a member of the community from buying your product.
Most people and businesses would already not want anyone obviously sick on the premises and they would be asked to leave or barred entry.