Wiktionary
n. a situation which offers no advantage to any particular side or group or person
Wikipedia
In commerce, a level playing field is a concept about fairness, not that each player has an equal chance to succeed, but that they all play by the same set of rules.
In a game played on a playing field, such as rugby, one team would have an unfair advantage if the field had a slope. Since some real-life playing fields do in fact have slopes, it is customary for teams to swap ends of the playing field at half time.
A metaphorical playing field is said to be level if no external interference affects the ability of the players to compete fairly.
Some government regulations are intended to provide such fairness, since all participants must abide by the same rules. However, they can have the opposite effect, for example if larger firms find it easier to pay for fixed costs of regulation. It may be added that if the rules affect different participants differently, then they are not actually the same.
Handicapping might be thought of as the opposite concept, of unequal rules designed to make the outcome of play more equal.
Usage examples of "level playing field".
I think 'fair' means that it's a level playing field, and everybody gets the same breaks, and that we don't punish Ken Griffey for hitting home runs.
And whatever new changes someone else may try to impose, you'll be starting fresh, from a level playing field, if you want to keep them off of Montana.
She'd always been of the opinion that if they were given a level playing field, women of any ability would do well.
Tinker accepted the bag and swung up onto her countertop in an effort to keep a level playing field.
He'd toyed with calling the place The Level Playing Field, but Kate's marketing judgment prevailed as she opined that it sounded like a sports shop and lacked a certain futuristic resonance, or as she put it, 'it's not nearly geeky enough'.
Garzia Nicosia, his companion since boyhood, was one of only a handful of men who had ever been able to speak to his master (his friend, his mentor) on something of a level playing field.