WiFi does not automatically equate to internet access. It is entirely possible to have WiFi networks without internet access. For example I have four WiFi networks in my house:
- The regular WiFi network that interconnects all my computers, iDevices, printers, scanners, postal scale, etc and connects all of them to the internet
- A "Guest" network that permits guests access to the internet but does not interconnect to any of the devcies on the first network.
- A special network used for home automation devices such as light switches, door locks, video doorbell, garage door opener but has only very limited and tightly controlled internet access.
- The last WiFi network interconnects the satellite television control/recorder to remote televisions in other rooms of the house. It connects directly to the satelite dish and has no internet connection.
If I had to guess I would suspect your unprotected networks were something like my fourth network or perhaps an ungaurded cellular "hot spot".
As to their speed there are many factors effecting that and without knowing
- actual signal strenght (the number of bars)
- the signal to noise ratio
- the actual protocol (802.11 a,b,g,n,ac)
- the type of connection to the internet
it would just be a shot in the dark.
Finally tapping into someone elses signal could be considered theft of services. For example if you are tapping into a WiFi connected through a cellular HotSpot you are using someone's download data without their permission and it is costing them real money.
