The short and clear answer is: "Yes."
My photography business is a legal registered business, so I MUST collect sales tax.
Different photographers have different ways to charge sales tax - if they have a legal business registered. Some include sales tax in their price, which makes it seems they don't charge sales tax on their photography services but in fact, they are still paying them.
Some choose to collect sales tax on top of their listed prices. I, as a photographer, choose this way simply for my own sanity and the ease of record keeping. If I do not charge sales tax on top of my services and products, the listed prices would have been higher to accommodate for the sales tax I am required to pay anyway. In any way you see it, the taxes must get paid.
I want to make it clear that I do NOT benefit anything from the amount of sales tax in any way. I collect sales tax on the behalf of California.
In my opinion, there are probably two reasons. They might not have a legal business registered or they might want to be more competitive in the eyes of their clients. In any way, if any photographer does not charge sales tax, then it is on them. Hopefully the IRS will not go after them and you do not have to deal with unregistered business.
Please note that I am NOT an expert at sales tax law. I am not a lawyer either. The blog should never be used to answer questions related to sales tax. Please consult your lawyers or do your own research if you want more information.