Twitter Will Show Who Pays for Ads and How Much They Spend

Probably because (and this is personal opinion, not researched facts) the US is in a huge advertising bubble. We have found out just how effective advertising is at selling products and we have numbers to back it up so and decent sized business is throwing money to advertisers like mad to drive sales. If sales start to drop though, they double down and throw more money for more advertising; but what they top level administrators aren't considering is the non-linear nature of advertising and exposure and eventually advertisee fatigue enough. By time the sales numbers come back for your second or third round you already paid for the advertising and just burned through tons of your initial profits for minor gains. At the end of it all though you likely still have positive overall numbers from advertising, they don't show how badly advertising performed per cost near the end because the big initial exposure brings up the average. Rinse and repeat!

Also, there aren't much of any protections for consumers against false and deceptive advertising unless you have a million dollar legal team to take on the business's multi-million dollar legal team.

Among many other reasons referenced by others, the users who would be willing to fork over a subscription fee to access twitter are exactly the demographic that twitter needs in order to keep its advertising attractive to marketers. A successful subscription option for a service like twitter would greatly diminish the value of their advertising inventory.