I understand that a trade tax would affect everyone, but for someone like me who makes maybe a handful of trades per month it wouldn't really do that much to dissuade me from making those trades. I also don't particularly care one way or the other what happens with HFT, I was just mentioning this as a thing people are thinking about.
My big concern with the transaction tax is how it applies to indexed funds/etfs. Those trade all the time so the price impact can be significant for those. Further, depending on implementation, you could easily get taxed multiple times for that as there is a transaction to get in/out of the index, and the internal index transactions.
