By Rabbi Chaim Chazzan
May one pick up someone who is waiting at a bus stop for a Jewish owned bus and give him a ride, thereby causing the company to lose the income of that customer?
If the person offering the ride would charge for the ride this would be a case of encroaching onsomeone else’s livelihood, which would be prohibited in this case where the profit definitely would have gone to the bus company. The issue of competition among businesses in halacha is particularly complex as it depends on both many unresolved halachic disputes and the particular business conditions.
As a rule of thumb, a distinction is made in halacha between opening a competing business that will eliminate the possibility of the first establishment to make a living (posek chayuso), such as a neighborhood that cannot sustain two stores selling the same product, which is prohibited, and a case where both could do business but opening a second store would cause the first to lose customers and thereby lose income,regarding which a shaila must be asked.
Even when the letter of the law permits one to enter into the field of expertise or commerce of one’s fellow, the Alter Rebbe writes in his Shulchan Aruch that it is a midas chassidus – an act of piety not to do so.
When one party invests in an attempt to make a profit, it is prohibited for another party to step in and reap the rewards of the first party’s efforts. (This is included in the halachic principle known as ani hamehapech becharara). In the case of picking up someone from a bus stop and charging for the ride, the bus company invested in advertising its service and that people should gather at this bus stop, therefore a taxi picking up someone waiting is considered reaping the rewards of the efforts of another.
However, in our case where the person giving the ride merely desires to do a favor and does not intend to charge the person waiting for the bus, it would be permitted. Chazal only prohibited taking the profit that another person worked to attain, but our case is analogous to a person giving his friend a gift to save him from needing to buy the item. Although the store owner lost the profit he would have received had the friend not given the present, the giver of the present has not taken anything that the store owner would have profited, and hencethere is no prohibition.
 ראה בכ”ז בשוע”ר חו”מ דיני הפקר והשגת גבול סי”ג, ובאמרי יעקב שם, פתחי חושן גניבה ואנאה פ”ט, אנציקלופדיה תלמודית ערך יורד לאומנות חבירו והדברים ארוכים.
 עי’ המצויין במקורות שבהע’ 1 בפרט בשו”ת חת”ס חו”מ סי’ קיח, משאת בנימין סי’ כז הובא בפ”ת חו”מ קנו, ג, צ”צ חו”מ סי’ כג
 שו”ת משיב בהלכה חו”מ סי’ ריב