Because before buybacks there were dividends. Did the difference between buybacks and dividends really make the difference between doing basic research and not?
Convert X% of a stocks value into a dividend and you pay taxes on that before you can buy more stock, but someone who keeps buying stock sees an exponential return. (Higher percentage of the company = larger dividends)
A company buys back X% of its stock functions like a dividend w/ stock purchase, but without that tax on dividends you’re effectively buying more stock. Adding a tax on stock buybacks could eliminate such bias, but it’s unlikely to happen any time soon.