The search looks for /usr/bin/ldapsearch nicht nur, aber auch in den
--provides.
search -sv zeigt dir, wo er es finrdet:

> hobbes:~ (104)# zypper se -sv --provides /usr/bin/ldapsearch
> S  | Name             | Type    | Version               | Arch   | Repository
> ---+------------------+---------+-----------------------+--------+----------------
> i  | openldap2-client | package | 2.4.46-150200.14.17.1 | x86_64 | repo-sle-update
>     filelist: /usr/bin/ldapsearch
> v  | openldap2-client | package | 2.4.46-150200.14.14.1 | x86_64 | repo-sle-update
>     filelist: /usr/bin/ldapsearch
> v  | openldap2-client | package | 2.4.46-150200.14.11.2 | x86_64 | repo-sle-update
>     filelist: /usr/bin/ldapsearch
> v  | openldap2-client | package | 2.4.46-150200.14.8.1  | x86_64 | repo-sle-update
>     filelist: /usr/bin/ldapsearch
> v  | openldap2-client | package | 2.4.46-150200.14.5.1  | x86_64 | repo-oss
>     filelist: /usr/bin/ldapsearch

The search looks for /usr/bin/ldapsearch - amongst others - in provides, but
finds matches in filelist only.
Other packages like bash additionaly provide some of their files explicitly.

> hobbes:~ (0)# zypper se -sv --provides /bin/bash
> S  | Name            | Type    | Version            | Arch   | Repository
> ---+-----------------+---------+--------------------+--------+-----------
>    | aranym          | package | 1.0.2-bp154.1.44   | x86_64 | repo-oss
>     filelist: /usr/share/aranym/afros/drive_c/bin/bash
> i  | bash            | package | 4.4-150400.25.22   | x86_64 | repo-oss
>     filelist: /bin/bash
>     filelist: /usr/bin/bash
>     filelist: /usr/bin/bashbug
>     provides: /bin/bash
>     provides: /usr/bin/bash
>    | bashdb          | package | 4.4_0.92-pm154.2.1 | noarch | packman
>     filelist: /usr/bin/bashdb
> >    | python3-bashate | package | 0.6.0-bp154.1.22   | noarch | repo-oss
    filelist: /usr/bin/bashate

That's this works:
> # zypper in /bin/bash
> Reading installed packages...
> '/bin/bash' not found in package names. Trying capabilities.
> 'bash' providing '/bin/bash' is already installed.

But this does not:
> # zypper in /usr/bin/ldapsearch

'Trying capabilities' should look into the filelist as well.