Loose connection when attaching an Arduino shield with header pins
The only alternative to soldering is a non soldering solution, like press fit headers. Unfortunately, this comes at the expense of A) Stacking, B) Reuse, as press fit headers pretty much destroy the holes, and C) cost.

Soldering is the only practical solution. Those are 0.1" or 2.54 mm standard through-hole sized spaced holes. Solder bridges are pretty difficult to do at that size unless you really overdo the solder. And even if you do, fixing it only requires some desoldering braid or a desoldering bulb.Its not like the ultra fine pitch you see in SMD parts. You have to intentionally screw up to cause a problem.