I can speak with reasonable knowledge only about US government and politics, but the mechanism here, and I strongly suspect nearly everywhere else, is something like this: Those with much to gain or lose over an issue make it a point to convey their perspective and wishes to those who manage the legal environment; those who are indifferent to the outcome, or stand to gain or lose little, do not. The legislators are beset by large numbers of such supplicants and have schedules chock full of meetings and other more or less obligatory activities. They do not normally have the time for more than superficial thought about the consequences, and their information about issues is biased strongly in favor of the views put forward by those with a big stake, and know implicitly that their vote will not greatly affect their reelection prospects.
The horrid copyright regime we have, that appears to be built into and extended by the TPP, TTIP, and similar agreements, is one example of a great many. It differs from the basic model only in that the proposed laws are being made by the executive branch in the form of treaties. The President's insistence on a straight up or down vote is simply an attempt to make sure the thing doesn't fall apart during the necessary legislative approval process.
Another example is the management of national security law and practice, where until recently the information givers have been aided by the substantially justifiable requirement for secrecy. This unfortunately also enabled companies with a substantial potential stake to finesse the issue and not push objections they might have had. Now that it is more in the open, they are beginning to behave normally and present their commercially motivated views publicly, and through lobbyists to senators and representatives.
An up and coming example is the concern for "infrastructure", presently focused on the railroads after the recent serious accident in New Jersey.
It is not obvious how to correct this fundamental problem, which probably is about equally prevalent everywhere and under all types of regime, although the details will differ.