It should be pointed out that while that is true, controlled burns need not be demolitions methods always. In addition to fire fighter training (often used by FD controlled facilities with structures that are designed to survive multiple fires) they are also used as garbage removal (usually burning leaf litter or yard waste, or large amounts of cut wood) and, ironically, to fight fires (usually to combat wild fires, controlled burns of empty wilderness land allow fire fighters to control or prevent a forest fire by burning the plant matter in an area, thus preventing an out of control wild fire from spreading to another area.).
In all cases, the inherit danger of losing control of the burn is present and changes in at a control burn can often result in things catching fire that weren't meant to catch fire.
As stated in other answers, the legalities of controlled burns depend on sub-naional laws, often state or even more likely county and local laws and ordinances as to when and where such controlled burns are permissible and they can even vary on seasonal variations (States like Florida, Texas, and Southern California do not have proper four seasons, but a wet and dry season. Burning might be restricted in Dry seasons as it's more likely to get out of control under these conditions, where as wet seasons will have a lot of soaked fuel that is more difficult to light by accident.). Generally, because of the size, matters related to restrictions based on climate and environment are managed by a state or local government depending on the size of the state and the variation of the climates (It's not a hard science. For example, there's more regional variation in climate in Maryland (which is generally divided into Western, Central, and Eastern and very diverse geography between the three regions has earned the state the unofficial nickname "America in Miniature" due to it having regions that mimic most U.S. landscapes) than there is in Florida, despite the fact that Florida is massive by land area and population in comparison but tends to have the same weather everywhere (Florida is the flattest state in the union).