There are traces of sodium chloride (salt) in most water to begin with. It's the level that is important. When people think of "salt in water", they tend to relate it to seawater, which contains very high levels of NaCl (Sodium chloride, salt) Therefore, they tend to think you are spraying seawater on their cars. That's a rather disturbing thought for any car owner. Although ignorant, it can still be their perception.
In a car wash with a reclaim system, yes salt can enter the system however, the levels are typically a fraction of seawater. No reclaim system on the market will remove the salt. Desalination is the proper method for removing the salt, however, in a car wash with a reclaim the levels are so low it's not required, or necessary.
If you have a reclaim system where roads are salted, it is important to remove the salt at some point as the salts (among other pollutants) are collective. Pumping your reclaim tanks periodically is highly recommended. With a good reclaim system, typically twice a year is sufficient. High volume sites will typically require quarterly pumping.