Every house with a radon problem can be fixed by a qualified contractor. However, most houses usually have multiple "routes" that the system piping can take. The radon contractor ishould work with the client in explaining what their options are and the associated costs for each.
Obviously, a system that is mounted on the outside of a home (back or side wall) is "seen". Many homeowners prefer this over having the system piping routed inside their home. The common challenge of routing pipes THROUGH a house is doing so in a "discreet manner". The most frequent approach is to hide them in closets. The problem in doing this often comes when multiple pipe penetrations are required to succesfully fix the probem! To use multiple pipes, the most "cost efficient" approach is to use "one" fan in the system (versus multiple systems). To do this, the pipes must be "merged" together and routed to the fan. Mitigators must "plan ahead" to make sure that "additional pipes" (if needed), don't have routing requirements for merging with the system that cross "finished space" where they will be 'seen". In a very small percentage of homes, this is simply "unavoidable". However, a competent contractor can offer to "box the piping in" so that "cosmetics" is no longer an issue! (This is usually done for an additional charge or the homeowner handles it themselves). It just depends on what look the homeowner is willing to live it!