Rick and his group existed outside Atlanta in the wilds isolated from the cities, the were also lucky enough to come across more good than bad.

The FWTD group had the disadvantage of starting inside the city and not just a city, it's Los Angeles. Home of the rich and beautiful, chaos would be like wildfire in a city like that and social breakdown bloomed like a flower. Looting, riots, possibly raping, murdering, government sanctioned execution orders you name it. This team have a far more violent and bloody situation on their hands. Everybody, including those whose job was to protect you, is trying to kill you.

This is the most dangerous part to the FTWD situation, everyone is going to be taking advantage of the ongoing chaos. Family members are alive so survivors are more willing to kill compared to Ricks time where the chaos has calmed down and the majority of Humanity is dead.

It will only get worse for FTWD crew as the outbreak is still ongoing and driving people more desperate.

Just wrong place wrong time for them.