example, I am in WA but most of my sales are in Utah because it is Aggie related sports memorabilia. Utah says I don't have to collect and pay sales tax in Utah unless I hit $100k in sales or 200 transactions. (See https://tax.utah.gov/sales/remote-sellers).

Many states have adopted this and I think they call is "having a nexus in the state". The problem with this is that you need to know the nexus rules for each state you have sales in.