If you live in housing like an apartment or condo they MUST have you sign for it. If you live in a single housing unit, its up to the UPS driver to make a judgment call. If you didn't sign for it you can file a claim. A lot of UPS drivers may deliver it to a neighbor and have them sign for it or leave a call tag for you to go get it at their office. It all depends on the neighborhood and the driver.
If you concerned about it, tell the shipper in an e-mail or on the order form to require a signature for delivery. In my case I ask them to NOT require a signature. Just a warning, I you do like If do, there is no way to file a claim.
In my case, The UPS and USPS know me by name. I ship hundreds of packages a week and receive 30-50 per week. Doesn't matter if they ship to my house or office they just deliver it to my office. I have had the same drivers (UPS and USPS) for many years and their routes covers both my home and business.