To address the OP. No it isn't poaching. There will always be people with cell phones, P&S, DSLR's, etc, shooting at events. If you take images that are considered valuable by another, than you are making some $$, just like the pre-established pro. There is nothing wrong with making a bit of money off of a hobby.
FWIW, I always defined amateur as someone who pursues something for pleasure, a business pursuing things for gain, and a professional as someone who is able to deliver the goods in a professional manner, no matter what the obstacles.
How do you think communities operate, on good intentions and promises? No revenue and no schools and services. You don't think it can happen, you're wrong. No sales tax revenue will result in other taxes like property taxes going up. You want services, the money has to come from somewhere.
Perhaps I and the other professionals should quit collecting and paying taxes so we can compete at a lower cost. Anything goes doesn't it? Each and every service provider should do this then.
Individuals dealing with individuals are a different story but they do get caught. There are plenty of us happy to turn them in.
It's true the world has changed and will never return to the old ways. I just see it as very sad that there's such a low level of integrity now.
For a long time, many communities were so gloriously civilized that they could and did operate on good intentions, promises, and those who treated others criminally (agression, theft, fraud, murder, etc) were punished appropriately. Civilization is now so advanced that the government can coercively take wealth from the individual to buy power as it sees fit, whether the individual consents or not. There was a time when forceful extraction of labor/productivity/wealth was considered theft, not integrity.
There are many in the world who do not want the second rate services that the government provides... but people such as this do not have a choice. Pay up or lose your income/property/freedom. History has demonstrated repeatedly that restrictions/regulations of the market are a windfall to those in control and a hindrance to those who are small...