how can it be "zero" ?

days of 7% was gone, but many still get around 5%.

the new deal is complicated, and they cannot give you a single number.
in fact for many TAs there is a % table according to how much they sell. there are also other incentives.
while for corporations the TA are also proposing some scheme of "fixed service fee".

anyway, i believe on average the business TA are still making a few percentages, and perhaps with a cap of, like you say, e.g. $300 (likely smaller)