Some states like New York and Wisconsin you couldn't win games. You could win extra ball(s) .

The games that were only made for this were called add-a-ball. Search IPDB for this name to see games made both ways.

With the coming of solid state games, it was changeable in the software to keep the games legal in some states.

LTG : )

This game has a fake add-a-ball mode, enabled by setting switch 14 off and switch 15 on. There is one extra ball per ball in play, even in this mode, as indicated by the "same player shoots again" lights. Once lit by crossing a score threshold, the alleged extra ball award will instead give 10000 points.

In a "true add-a-ball" game, you could achieve extra balls by score and by feature-based extra ball awards during the same ball-in-play, and have them all stacked up.
.................David Marston

Same deal with the earlier Bally EMs with Add-A-Ball conversion kits, that just enables "shoot again" (I wired one for Rocket III).

Misleading marketing to compete with true AAB machines and enable sales into the restricted states I guess.

Add-a-ball was common with Gottlieb 1-player games. The game would start with 5 'balls to play' and count down to 0 unless you hit a special or award threshold in wich it would bump up 'balls to play'.

Bally never had that. Instead there is an adjustment for Special or Replay award(s). An operator could choose between, replay, extrra Ball, or points.
This was all to satisfy jurisdictions like New York where awarding free games was considered somethng of value making pinball a gambling device by local law.