There are already a lot of things that are feasible without any license. In Europe/CEPT, you might have a look at all bands under the provisions of ERC Recommendation 70-03 (https://docdb.cept.org/download/2464).
However, those provisions are made in order to ensure a good/fair access to anyone, and therefore to prevent a single user or single technology from overusing those bands which are meant to be shared. For that purpose, there are associated restrictions (in terms of power/EIRP, duty-cycle) and/or mandatory sharing approaches (Listen-before-talk, detect-and-avoid, etc.). In the case of Wi-Fi, CSMA/CA is a form of listen-before-talk.
Unfortunately, mobile technologies defined at 3GPP (GSM, HSPA, LTE, NR) are not designed to be used in such a way (i.e. they don't have any sharing mechanism such as LBT and they require _by design_ dedicated/licensed bands), which by the way implies some kind of specific coordination at the country borders where two operators are using the same channels... (you might look at ECC recommendation 15-01 for an example of PCI sharing).
LAA is a way to have an LTE carrier within the (shared) 5 GHz band, but it has to rely on an anchor carrier for signaling, which requires licensed spectrum. Multefire is a fully-unlicensed solution, but I doubt many UEs (smartphones) support it, and anyway because it must implement the same power limitations and LBT as wi-fi in order to comply with regulations I doubt it would be much better than wi-fi... (maybe it would in some specific case where deterministic QoS is important)
One more thing : keep in mind that a typical 3G/4G/5G macrocell site (e.g. around 65 dBm EIRP per carrier) is something very expensive : your mileage may vary but it can easily be around 100000 € / site when some construction is required.
>LAA is a way to have an LTE carrier within the (shared) 5 GHz band, but it has to rely on an anchor carrier for signaling, which requires licensed spectrum.
I want to add, as I said in my last comment that 5G NR allows for 5Ghz to be used as primary carrier, it was controversially included in the standard. A study from earlier this month showed LAA apparently doesn't play too well with wifi nearby: https://www.cs.uchicago.edu/news/article/laa-wifi/
In general, cellular technologies have been designed against assumptions of a clean (or at least exclusively used) RF channel. 4G and 5G are deployed with frequency reuse between base stations, which implement the same standard and can coordinate their emissions and scheduling of clients (both in time and frequency) to minimise interference.
WiFi is a whole different kettle of fish - it's designed to be used by multiple independent access point operators simultaneously, with the ability to change frequency if needed based on the interference observed. It's designed to try to deliver good performance by listening before transmitting etc, to avoid transmitting over another device, to avoid a tragedy of the commons scenario where selfish devices end up rendering WiFi unusable for everyone (including themselves), through refusing to yield time to devices transmitting on other networks.
NR-U and LAA etc don't generally play according to the same rules, as they're standards arising from the world of exclusive spectrum access, and coordination of base stations by one operator - in the world of cellular, the base stations allocate uplink channels for their clients. That doesn't work in WiFi with multiple networks in the same approximate location, hence they need to try to prevent interference and cross-talk.
However, those provisions are made in order to ensure a good/fair access to anyone, and therefore to prevent a single user or single technology from overusing those bands which are meant to be shared. For that purpose, there are associated restrictions (in terms of power/EIRP, duty-cycle) and/or mandatory sharing approaches (Listen-before-talk, detect-and-avoid, etc.). In the case of Wi-Fi, CSMA/CA is a form of listen-before-talk.
Unfortunately, mobile technologies defined at 3GPP (GSM, HSPA, LTE, NR) are not designed to be used in such a way (i.e. they don't have any sharing mechanism such as LBT and they require _by design_ dedicated/licensed bands), which by the way implies some kind of specific coordination at the country borders where two operators are using the same channels... (you might look at ECC recommendation 15-01 for an example of PCI sharing).
LAA is a way to have an LTE carrier within the (shared) 5 GHz band, but it has to rely on an anchor carrier for signaling, which requires licensed spectrum. Multefire is a fully-unlicensed solution, but I doubt many UEs (smartphones) support it, and anyway because it must implement the same power limitations and LBT as wi-fi in order to comply with regulations I doubt it would be much better than wi-fi... (maybe it would in some specific case where deterministic QoS is important)
One more thing : keep in mind that a typical 3G/4G/5G macrocell site (e.g. around 65 dBm EIRP per carrier) is something very expensive : your mileage may vary but it can easily be around 100000 € / site when some construction is required.