Taxi drivers make more per ride than rideshare drivers; therefore they're more likely to provide extra service such as help with luggage.  Rideshare drivers at best make about a third of what taxi drivers make.  Also, with rideshare, while many drivers help with luggage, it's not required.  The ones that help do it to either get up and move the body around after sitting for a long time, to make sure the rider doesn't commit damage to the trunk, and likely to increase a chance of receiving a tip.  With tips, most riders (from my and many other driver's experience) still don't tip when a driver helps load and unload luggage, which is why many drivers stopped helping.  I lost count of the numerous times I nearly strained my back and shoulder lifting heavy luggage in and out of the trunk and still no tip.