It is the duty of the owner of real property abutting a portion of a street improved by a street betterment (whether said street betterment was constructed, erected or made at the instance or request of such owner or any predecessor in interest of such owner, or not) to maintain said street betterment on such portion of such street abutting such owner's real property in such condition that the same shall not endanger persons or property, and to maintain the same in a condition which will not interfere with the public convenience or safety in the use of such street betterment, save and except as to those conditions created or maintained in, upon, along, across, under or over said street by any person other than the owner under and by virtue of any permit issued hereunder or any right to them granted by law or by the legislative body of the city, and such persons shall be under a like duty in relation thereto. (Prior code § 75014)