It’s because the left is very concerned about the balancing of powers, while the right tends to be very concerned with wielding it. We progressives are generally uncomfortable with power, and conflicted about how to use it wisely — in some sense I would say it is one of our greatest weaknesses (because we can often be slow to act), along with failing to comprehend the opposition (or even acknowledging that there is opposition and that it must be addressed to achieve objectives).
However, it is also one of our greatest strengths — and applying more caution to the forceful use of power is something I would identify as being less developed on the right. It is confusing, and seemingly contradictory, to many of us on the left to hear the right’s message of limited government and personal freedom when it is so often combined with numerous, heavy-handed attempts to exert social control over the activities of citizens even in complete privacy and with mutual consent.
Progressives also tend to be more uncomfortable with money and issues of finance. We have a heightened sensitivity to perceived corruption, which tends to lead to ham-fisted attempts to “get the money out of politics!” We don’t always realize that sometimes, the money is a red herring — and that many times corruption can exist even more deeply when it’s not currency (or currency alone) that is changing hands.
It is also in these realms of power and money that we on the left tend to be at our most histrionic, but least well-informed: because we are a little bit afraid and/or turned off at the idea of “going more deeply” into these realms to gain the knowledge we need to thoroughly understand the complex chess games being played (we even tend to outright reject the idea that it is a game, because we sense a certain baseline level of unfairness in all games — because the rules have most commonly been set elsewhere, without our participation or consent — and we desperately wish to escape the need to constantly feel like players within our own lives).