In 2018 I left the speed trials and went to a wind tunnel on the east coast with the bike. It was day-by-day travel with no preplanned campground reservations. Every day I used the group network at the KOA campground, Starbucks, a truck stop, or other place to make reservations for the next night or to order supplies like new trailer tires. Credit card info was sent over the i-net to do this and many of these networks were not secure. Someone hacked into my info and made fraudulent charges. They did not get money from me but it was a pain in the donkey to deal with the situation while on the road. This tether method gives more security.
Like TD says, some mobile plans have limits on the data you can transmit each month unless you pay more money. My el-cheapo plan gives me enough capacity to conduct business, read e-mails, look at Landracing dot com, the weather, and the news. Streaming uses up the capacity real quick and I do not do it.