Is it illegal to pull out of a business with out using a turn signal?

Answer 1

The uniform traffic laws may be applied to traffic on privately owned roadways that are used by the public. Most frequently the requirement to signal your turn onto a public roadway from a private roadway would be cited after an incident or accident. The following is Florida law (see link), other states will have similar provisions.

A municipality may exercise jurisdiction over any private road or roads, or over any limited access road or roads owned or controlled by a special district, located within its boundaries if the municipality and party or parties owning or controlling such road or roads provide, by written agreement approved by the governing body of the municipality, for municipal traffic control jurisdiction over the road or roads encompassed by such agreement.

Or, to put it another way, the uniform traffic laws may not be applied to privately owned land unless the owner of that land has previously agreed to this in writing and that agreement has been approved by the local authority. Private land is private unless and until the owner waives some of his rights to privacy.

You, short of contacting the owner or manager of the property, would have no ready means of ascertaining that such an agreement might be in effect. A prudent person would, therefore, obey all traffic rules, including signalling his intent to turn, while driving on private property.