Joe Lucky, I've healed a whole bunch of these in me. I relied on homemade exposure therapy and CBT. My level of distress to these daily things (spiders, balloons, etc) was really interfering with my adult life.
I started with spiders, because my extreme phobia and response to my phobia was going to end a beloved job if I didn't. In that case, my homemade exposure therapy was like this (in a process taking weeks, not minutes):
1. With a teeny, tiny unmoving spider, don't run screaming. (I was still allowed to run/freeze, etc, near large or moving ones.)
2. With same, stay in the same room as it for some seconds.
3. With same, take one step toward it.
4. With same, get closer and closer to it.
5. With same, stand peacefully near.
6. With same, touch one almost imperceptibly. Now that size was complete.
7. Work my way up to bigger and bigger ones.
Yesterday, I found a big one, scooped him up in a cup, enjoyed looking at him for some minutes, then set him free outside. Last year, I had a "pet" spider, keeping me company during a month of bed rest in the corner nearest my feet.
I wouldn't impose exposure therapy on another person, including on my own kid. It's different when we choose it for ourselves. But there are many excellent, gentle resources out there. As we see in this thread, people don't always age out of this stuff. It's often worth healing in childhood (easier, plus child doesn't suffer for years in the meantime, plus difficult neural traits aren't cemented).
My kid is fine with spiders and balloons, but newly has some light OCD things. He (11) has been teaching himself CBT techniques via some phenomenal books on kid-OCD and kid-persistent worry. I ordered into our library all the kid books on this page:
http://www.parentbooks.ca/Obsessive-Compulsive_Disorder.html He loves them and has been having solid success. A lot of these books are for kids much younger than him, and are intended for the parent and child to use together. The material in some is so intelligent and helpful, I would recommend them for adults too!
Besides these approaches, one session of EMDR resolved a huge fear my kid had when he was younger (we've been unable to find an EMDR practitioner here who will work with kids, so not an option currently), and intensive nutritional approaches resolved some weird OCDs in me.