Visiting a national park in any country obligates the visitor to abide by local rules and to not destroy the very environment they have come to see. U.S. authorities need to have the power to punish the offenders; otherwise the rules might as well not exist. U.S. tourists abroad are also obligated to follow local laws there.
The Chinese tourist who collected thermal water in Yellowstone was actually fined $1,000. Yellowstone National Park maintains certain rules which are actually safety guidelines and helps protect tourists from unforeseen accidents. The park houses several natural resources and tourists should respect the rules. Tourists or anyone collecting thermal water from Yellowstone should definitely be fined.
In order to collect the thermal water, the Chinese tourist had to ignore the signs and walkways. He had to specifically break the rules to get close to the water. Thermal water in Yellowstone is no joke. In the park's history, people and pets have often died by falling into the thermal water because it basically boils them alive. It is incredibly dangerous for tourists to get too close to these thermal waters, and it is also very dangerous for anyone who might need to rescue them afterward. The fine for the Chinese tourist is appropriate because he broke the laws that were meant to keep him safe.
NO, the tourist should not have been fined for walking off a boardwalk at Yellowstone National Park and collecting thermal water unless there was a sign present that let the tourist know that this was prohibited. Tourists often do not know the rules of a country. Strange and arbitrary rules should not be enforced without a warning.