Why do most countries today have mixed economies?

[Wonders]

Also what elements of a market economy do you see in Los Angeles?

[A.J]

Most countries are government ruled and developing countries not mixed

[tacomadc]

Because a country needs the advantages of a free market, capitalistic economy to stimulate jobs and business, but also a socialistic net to help out the less fortunate, sick and poor so you don't have people dying in the streets from starvation while we pay farmers not to grow crops.
In Los Angeles there is a huge influx of people from Mexico and other countries. Many of them rely on social aid when they immigrate and later, but the real reason they come is to work - good old capitalism!!! (not socialism at all).

[Ayo A]

because they take what is good from both socialism and capitalism and make the most of them. Besides, there is no absolute capitalism or absolute socialism.

I didn't know Loas Angeles has it's own economic model.wonder what that is though.

[Victor]

As long as a government (local, state or national) taxes its businesses and households, there will be a mixed economy. Governments have no money of their own: only what they take by taxes or duties from other economic entities. Those funds are then used for community or social or political ends and therefore are under the control of government agencies. Those agencies may be state (legislated) corporations, government departments, private companies working to public contracts or "public-private partnerships" in UK and other parts of Europe. Either way, at that point, the public sector is making economic decisions and the mixed economy has arrived.

In most big cities, local government influences the local economy by its expenditure on roads, education, welfare, environment and so on. The money is derived form taxes, duties and some charges for services, and represents a redistribution of income and wealth from some sectors to others. If Los Angeles engages in public education, highway maintenance, welfare housing or transportation, then the city council is involved in the local economy and is influencing decisions taken by private business and by households.

In some USA cities, local governmental spending accounts for up to 20 per cent of all regional expenditure and they are the main locus for employment, health and welfare services, and logistic management. I'm not sure of LA, but the city accounts will show their income and expenditure, and the enterprises in which they are engaged. If you can't see these details, then LA is breaking the law and should be more transparent about its engagement in and with businesses.