Well i think you need to help them understand the difference between the traditional realm of local people competing with them and possibly their storefront and with the new online search realm of people finding them via searches.
If they are a traditional business where people find them via their physical storefront and through other traditional means, then that will prove more valuable to them.
However, i'm assuming they hired you because business is down. If that's the case, you just need to make the case for using non-traditional methods including online search which will boost their sales. In which case, you really need to define what their keywords are before you find their search competition.
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