This is not a question but a posting to help other travelers avoid a situation we encountered at the Florence Italy Train Station.
If you purchase a Trenitalia train ticket at the vending machines in the Florence train station you must scan the bar code on the ticket at a scanner to validate the ticket---this prevents reuse of the ticket. These scanners are located throughout the station, including at the platform before you board the train. This scanning/validation process can be done by you without any assistance at the scanner which is very easy to use.
Beware of the following. On our first visit to the Florence train station to take a local train to Siena (no reserved seating), we did not fully understand the process and at the platform we encountered a man (I don't think he was an employee of Trenitalia) who insisted (and I mean insisted) on taking our ticket and validating it through the scanner for us. He then said he would escort us to seats on the train where he, of course, demanded a not insignificant tip.
Most people probably don't need any help in either scanning the ticket or finding a seat on the train. If anyone tries to "assist" you, and you don't want to pay a tip for basically nothing, just go to another scanner---they are located throughout the station or, better yet, scan the ticket before actually going to the platform and proceed directly onto the train avoiding these folks.